[lldb][DWARFASTParserClang][NFC] Make ParsedDWARFTypeAttributes parameter a const-ref (#183024)
In https://github.com/llvm/llvm-project/pull/182956 we stopped using
access specifiers from DWARF for most Clang decls we create. This
parameter no longer needs to be modified and we can make it a
`const-ref`.