Introduces `__builtin_hlsl_buffer_update_counter` clang buildin that is
used to implement the `IncrementCounter` and `DecrementCounter` methods
on `RWStructuredBuffer` and `RasterizerOrderedStructuredBuffer` (see
Note).
The builtin is translated to LLVM intrisic `llvm.dx.bufferUpdateCounter`
or `llvm.spv.bufferUpdateCounter`.
Introduces `BuiltinTypeMethodBuilder` helper in `HLSLExternalSemaSource`
that enables adding methods to builtin types using builder pattern like
this:
```
BuiltinTypeMethodBuilder(Sema, RecordBuilder, "MethodName", ReturnType)
.addParam("param_name", Type, InOutModifier)
.callBuiltin("buildin_name", { BuiltinParams })
.finalizeMethod();
```
Fixes#113513
[First version](llvm/llvm-project#114148) of this PR was reverted
because of build break.
cac978331f