[flang] Emit "raw" name for procedure interface in module file (#83915)

Save both the raw procedure interface symbol as well as the result of
passing it through GetUltimate() and BypassGeneric() in symbol table
entries with ProcEntityDetails. The raw symbol of the interface needs to
be the one used for emitting procedure symbols to module files.

Fixes https://github.com/llvm/llvm-project/issues/83836.