We can drop .str().c_str() here because all of the following are of
type StringRef:

- E.Name
- the second parameter of llvm::yaml::IO::enumCase
- the second parameter of llvm::yaml::IO::bitSetCase

Identified with readability-redundant-string-cstr.

This patch updates the frontend to support version 1.2 of root
signatures, it adds parsing, metadata generation and a few tests.

---------

Co-authored-by: joaosaffran <joao.saffran@microsoft.com>

This PR is updating `Object/DXContainer.h` so that we can read data from
root signature version 1.2, which adds flags into static samplers.

This PR updates the YAML representation of DXContainer to support Root
Signature 1.2, this also requires updating the write logic to support
testing.

This PR is updating Root Signature YAML to use enums, this is a required
change to remove the use of to_underlying from DirectXContainer binary
file.

Closes: [#150676](https://github.com/llvm/llvm-project/issues/150676)

This pr fixes some inconsistencies in behaviour of how we handle
`StaticSamplersOffset` with respect to DXC and `RootParameterOffset`.
Namely:

1. Make codegen of `RTS0` always compute the `StaticSamplersOffset`
regardless if there are any `StaticSampler`s. This is to be consistent
and produce an identical `DXContainer` as DXC.
2. Make the `StaticSamplersOffset` and `RootParametersOffset` optional
parameters in the yaml description. This means it will be used when it
is specified (which was not necassarily the case before).
3. Enforce that the provided `StaticSamplersOffset` and
`RootParametersOffset` in a yaml description match the computed value.

For more context see:
https://github.com/llvm/llvm-project/issues/155299.

Description of existing test updates updates:
- `CodeGen/DirectX/ContainerData`: Updated to codegen computed values
(previously unspecified)
- `llvm-objcopy/DXContainer`: Updated to `yaml2obj` computed values
(previously unspecified)
- `ObjectYAML/DXContainer`: Updated to `yaml2obj` computed values
(previously incorrect)
- `ObjectYAML/DXContainerYAMLTest`: Updated to `yaml2obj` computed
values (previously incorrect)

See newly added tests for testing of optional parameter functionality
and `StaticSamplersOffset` computation.

Resolves: https://github.com/llvm/llvm-project/issues/155299

This pr removes the redundancy of having the same enums defined in both
the front-end and back-end of handling root signatures. Since there are
many more uses of the enum in the front-end of the code, we will adhere
to the naming conventions used in the front-end, to minimize the diff.

The macros in `DXContainerConstants.def` are also touched-up to be
consistent and to have each macro name follow its respective definition
in d3d12.h and searchable by name
[here](https://learn.microsoft.com/en-us/windows/win32/api/d3d12/).

Additionally, the many `getEnumNames` are moved to `DXContainer` from
`HLSLRootSignatureUtils` as they we will want them to be exposed
publicly anyways.

Changes for each enum follow the pattern of a commit that will make the
enum definition in `DXContainer` adhere to above listed naming
conventions, followed by a commit to actually use that enum in the
front-end.

Resolves https://github.com/llvm/llvm-project/issues/145815

As pointed in #145438, the order of elements in `v2::DescriptorRange` is
wrong according to the root signature file format. This changes the
order and updates the code and test to continue to pass.

Closes: #145438

---------

Co-authored-by: joaosaffran <joao.saffran@microsoft.com>

- Adds support for static samplers ins dxcontainer binary format.
- Adds writing logic to mcdxbc
- adds reading logic to Object
- adds tests
Closes: [126636](https://github.com/llvm/llvm-project/issues/126636)

---------

Co-authored-by: joaosaffran <joao.saffran@microsoft.com>

Closes:
https://github.com/orgs/llvm/projects/4/views/22?sliceBy%5Bvalue%5D=joaosaffran&pane=issue&itemId=97332852&issue=llvm%7Cllvm-project%7C126635

---------

Co-authored-by: joaosaffran <joao.saffran@microsoft.com>