Reverts llvm/llvm-project#152537

Broke the build in some cases. Need to investigate more for a proper
solution.

This pr implements support for a root signature as a target, as specified
[here](https://github.com/llvm/wg-hlsl/blob/main/proposals/0029-root-signature-driver-options.md#target-root-signature-version).

This is implemented in the following steps:
1. Add `rootsignature` as a shader model environment type and define
`rootsig` as a `target_profile`. Only valid as versions 1.0 and 1.1
2. Updates `HLSLFrontendAction` to invoke a special handling of
constructing the `ASTContext` if we are considering an `hlsl` file and
with a `rootsignature` target
3. Defines the special handling to minimally instantiate the `Parser`
and `Sema` to insert the `RootSignatureDecl`
4. Updates `CGHLSLRuntime` to emit the constructed root signature decl
as part of `dx.rootsignatures` with a `null` entry function
5. Updates `DXILRootSignature` to handle emitting a root signature
without an entry function
6. Updates `ToolChains/HLSL` to invoke `only-section=RTS0` to strip any
other generated information

Resolves: https://github.com/llvm/llvm-project/issues/150286.

##### Implementation Considerations
Ideally we could invoke this as part of `clang-dxc` without the need of
a source file. However, the initialization of the `Parser` and `Lexer`
becomes quite complicated to handle this.

Technically, we could avoid generating any of the extra information that
is removed in step 6. However, it seems better to re-use the logic in
`llvm-objcopy` without any need for additional custom logic in
`DXILRootSignature`.

The OpaqueValueVisitor was not correctly traversing the AST to find all
OpaqueValueExprs. This resulted in some expressions not being correctly
initialized. This change fixes the visitor to correctly traverse the
AST.

Fixes https://github.com/llvm/llvm-project/issues/156786

This is the first PR to implement the semantics proposal:
https://github.com/llvm/wg-hlsl/blob/main/proposals/0031-semantics.md

This PR focuses on the changes required to handle user semantics, but
tried to be almost NFC.
What changes is the error messages as the semantics case is not kept
when reporting error messages.

You might notice the SV_GroupIndex semantic is not properly validated as
are others. This is an existing behavior that we'll need to fix, but
wanted to keep this separated from this rewrite to stay as-close as an
NFC as possible.

The next PR will add support on the different kinds of I/O we can have
using semantics (input, inout param, structs).

Adds assert as requested in
https://github.com/llvm/llvm-project/pull/152454#discussion_r2304509802.

Adds support for accessing sub-arrays from fixed-size multi-dimensional global resource arrays.

Enables indexing into globally scoped, fixed-size resource arrays that have multiple dimensions when the result is a smaller resource array. 

For example:

```
RWBuffer<float> GlobalArray[4][2];

void main() {
  RWBuffer<float> SubArray[2] = GlobalArray[3];
  ...
}
```

The initialization logic is handled during codegen when the ArraySubscriptExpr AST node is processed. When a global resource array is indexed and the result type is a sub-array of the larger array, a local array of the resource type is created and all elements in the array are initialized with a constructor call for the corresponding resource record type and binding.

Closes #145426

Removes uniformity bit from resource initialization intrinsics `llvm.{dx|spv}.resource.handlefrombinding` and `llvm.{dx|spv}.resource.handlefromimplicitbinding`. The flag currently always set to `false`. It should be derived from resource analysis and not provided by codegen.

Closes #135452

This reintroduces `Type.h`, having earlier been renamed to `TypeBase.h`,
as a redirection to `TypeBase.h`, and redirects most users to include
the former instead.

This is a preparatory patch for being able to provide inline definitions
for `Type` methods which would otherwise cause a circular dependency
with `Decl{,CXX}.h`.

Doing these operations into their own NFC patch helps the git rename
detection logic work, preserving the history.

This patch makes clang just a little slower to build (~0.17%), just
because it makes more code indirectly include `DeclCXX.h`.

This is a preparatory patch, to be able to provide inline definitions
for `Type` functions which depend on `Decl{,CXX}.h`. As the latter also
depends on `Type.h`, this would not be possible without some
reorganizing.

Splitting this rename into its own patch allows git to track this as a
rename, and preserve all git history, and not force any code
reformatting.

A later NFC patch will reintroduce `Type.h` as redirection to
`TypeBase.h`, rewriting most places back to directly including `Type.h`
instead of `TypeBase.h`, leaving only a handful of places where this is
necessary.

Then yet a later patch will exploit this by making more stuff inline.

Adds support for accessing individual resources from fixed-size global resource arrays.

Design proposal:
https://github.com/llvm/wg-hlsl/blob/main/proposals/0028-resource-arrays.md

Enables indexing into globally scoped, fixed-size resource arrays to retrieve individual resources. The initialization logic is primarily handled during codegen. When a global resource array is indexed, the
codegen translates the `ArraySubscriptExpr` AST node into a constructor call for the corresponding resource record type and binding.

To support this behavior, Sema needs to ensure that:
- The constructor for the specific resource type is instantiated.
- An implicit binding attribute is added to resource arrays that lack explicit bindings (#152452).

Closes #145424