Fix symbol printing in the language server for a few cases

[jabraham17]

Fixes how symbols are printed in the language server for a few cases

• new expressions like new (foo())()
• types like owned C, sync int, and atomic real
• postfix expressions like foo! and unmanaged C?

Additionally, when resolving these I fixed an issue where locations for something like var x: int; reported the location as including the ;. This is complicated by how we handle the default location for null rules in the grammar, but can be worked around by selectively setting the location in a few _opt cases.

Tested that make test-cls works, make test-frontend works, and start_test test/errors works

[Reviewed by @DanilaFe and @dlongnecke-cray]