rr::ConstantData() returns a Pointer<Byte> to an immutable copy of the provided data.

Added two new variants of rr::Call() for calling member function pointers.

Added tests.

Bug: b/143479561
Change-Id: I5846fb313fbd81821bf4e9bb655414a5e0eaf133
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/38408Tested-by: Ben Clayton <bclayton@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>