[Clang] Add a new warning to warn when passing uninitialized variables as...

[Clang] Add a new warning to warn when passing uninitialized variables as const reference parameters to a function

Summary:
Add a new warning -Wuninitialized-const-reference as a subgroup of -Wuninitialized to address a bug filed here: https://bugs.llvm.org/show_bug.cgi?id=45624

This warning is controlled by -Wuninitialized and can be disabled by -Wno-uninitialized-const-reference.
The warning is diagnosed when passing uninitialized variables as const reference parameters to a function.

Differential Revision: https://reviews.llvm.org/D79895