[HLSL][RootSignature] Update `setDefaultFlags` to account for Root Signature Version (#145828)
This pr updates `setDefaultFlags` in `HLSLRootSignature.h` to account
for which version it should initialize the default flag values for.
- Updates `setDefaultFlags` with a `Version` argument and initializes
them to be compliant as described
[here](https://github.com/llvm/wg-hlsl/pull/297).
- Updates `RootSignatureParser` to retain the `Version` and pass this
into `setDefaultFlags`
- Updates all uses of `setDefaultFlags` in test-cases
- Adds some new unit testing to ensure behaviour is as expected and that
the Parser correctly passes down the version
Resolves https://github.com/llvm/llvm-project/issues/145820.