[wasm] Correctly escape library names when generating symbols for .c (#79007)

[wasm] Correctly escape library names when generating symbols for .c (#79007)

* [wasm] Correctly escape library names when generating symbols for .c files.
Use the existing `FixupSymbolName` method for fixing library names too,
when converting to symbols.

* [wasm] *TableGenerator task: Cache the symbol name fixups
.. as it is called frequently, and for repeated strings. For a
consolewasm template build, we get 490 calls but only 140 of them are
for unique strings.

* Add tests

Fixes https://github.com/dotnet/runtime/issues/78992 .