[clang] [Driver][BoundsSafety] Add -fbounds-safety-experimental flag (PR #70480)

[Dan Liew via cfe-commits]

================
@@ -330,6 +330,9 @@ def warn_alias_with_section : Warning<
   "as the %select{aliasee|resolver}2">,
   InGroup<IgnoredAttributes>;
 
+def error_bounds_safety_lang_not_supported : Error<
----------------
delcypher wrote:

Should we introduce a "bounds safety" category and have the diagnostics fall under that. E.g. like the `let CategoryName = "Instrumentation Issue" in` code below?

https://github.com/llvm/llvm-project/pull/70480