[HLSL] Resource initialization by constructors (#135120)
- Adds resource constructor that takes explicit binding for all resource
classes.
- Updates implementation of default resource constructor to initialize
resource handle to `poison`.
- Removes initialization of resource classes from Codegen.
- Initialization of `cbuffer` still needs to happen in `CGHLSLRuntime`
because it does not have a corresponding resource class type.
- Adds `ImplicitCastExpr` for builtin function calls. Sema adds these
automatically when a method of a template class is instantiated, but
some resource classes like `ByteAddressBuffer` are not templates so they
need to have this added explicitly.
Design proposal: llvm/wg-hlsl#197
Closes #134154
