[analyzer] Propagate taint for wchar variants of some APIs (#66074)

Functions like `fgets`, `strlen`, `strcat` propagate taint.
However, their `wchar_t` variants don't. This patch fixes that.

Notice, that there could be many more APIs missing.
This patch intends to fix those that so far surfaced,
instead of exhaustively fixing this issue.

https://github.com/llvm/llvm-project/pull/66074