We'd introduced separate versions of `llvm.dx.resource.load` with a
struct return to handle the CheckAccessFullyMapped case without making
the IR for the common case unnecessarily complicated. However, at this
point the common case is really `resource.getpointer`, so the ergonomics
of a simplified version of `load` don't actually gain us as much as the
cost of having multiple opcodes.

Drop the `dx.resource.loadchecked` functions and have `dx.resource.load`
consistently return `{element_type, i1}`.

Rename HLSL resource-related intrinsics to be consistent with the naming
conventions discussed in [wg-hlsl:0014].

This is an entirely mechanical change, consisting of the following
commands and automated formatting.

```sh
git grep -l handle.fromBinding | xargs perl -pi -e \
  's/(dx|spv)(.)handle.fromBinding/$1$2resource$2handlefrombinding/g'
git grep -l typedBufferLoad_checkbit | xargs perl -pi -e \
  's/(dx|spv)(.)typedBufferLoad_checkbit/$1$2resource$2loadchecked$2typedbuffer/g'
git grep -l typedBufferLoad | xargs perl -pi -e \
  's/(dx|spv)(.)typedBufferLoad/$1$2resource$2load$2typedbuffer/g'
git grep -l typedBufferStore | xargs perl -pi -e \
  's/(dx|spv)(.)typedBufferStore/$1$2resource$2store$2typedbuffer/g'
git grep -l bufferUpdateCounter | xargs perl -pi -e \
  's/(dx|spv)(.)bufferUpdateCounter/$1$2resource$2updatecounter/g'
git grep -l cast_handle | xargs perl -pi -e \
  's/(dx|spv)(.)cast.handle/$1$2resource$2casthandle/g'
```

[wg-hlsl:0014]: https://github.com/llvm/wg-hlsl/blob/main/proposals/0014-consistent-naming-for-dx-intrinsics.md

DXIL spec for reference:
[DXIL.rst](https://github.com/microsoft/DirectXShaderCompiler/blob/5704c4744e8752adf5c1bacbf94638f30ff330fd/docs/DXIL.rst?plain=1#L2330).

This represents a typedBufferLoad that's followed by
"CheckAccessFullyMapped". It returns an extra `i1` representing that
value.

Fixes #108085

The `@llvm.dx.typedBufferLoad` intrinsic is lowered to `@dx.op.bufferLoad`.
There's some complexity here in translating to scalarized IR, which I've
abstracted out into a function that should be useful for samples, gathers, and
CBuffer loads.

I've also updated the DXILResources.rst docs to match what I'm doing here and
the proposal in llvm/wg-hlsl#59. I've removed the content about stores and raw
buffers for now with the expectation that it will be added along with the work.

Note that this change includes a bit of a hack in how it deals with
`getOverloadKind` for the `dx.ResRet` types - we need to adjust how we deal
with operation overloads to generate a table directly rather than proxy through
the OverloadKind enum, but that's left for a later change here.

Part of #91367

Pull Request: https://github.com/llvm/llvm-project/pull/104252