[clang] [UBSAN] [FC] add null, alignment and array-bounds checks (PR #190739)

[VASU SHARMA via cfe-commits]

vasu-the-sharma wrote:

> Hi team, this is the 3rd and final PR containing the code changes along with test coverage updations. Please review this PR. @tonykuttai @midhuncodes7 @hubert-reinterpretcast @jakeegan Thanks.

ping
@tonykuttai @midhuncodes7 @hubert-reinterpretcast @jakeegan 

https://github.com/llvm/llvm-project/pull/190739