Add a new `CreateIntrinsic` overload with no `Types`, useful for
creating calls to non-overloaded intrinsics that don't need additional
mangling.

This change makes it consistent with other uses of ubsantrap.

This also updates the tests. Notably, BoundsChecking/runtimes.ll had guard=3 which passed only because the method of calculating the parameter (`IRB.GetInsertBlock()->getParent()->size()`) happened to give the same answer.

And use that as an argument for
allow_ubsan_check when needed.

Other ubsan checks use SanitizerKind,
but those are known to the clang only.

So make it a parameter in LLVM.

Should be NFCI as we run sanitizer, like msan, before local-bounds.

Remove ReportingMode and ReportingOpts.

#120613 removed -ubsan-unique-traps and replaced it with
-fno-sanitize-merge (introduced in #120511), which allows fine-grained
control of which UBSan checks to prevent merging. This analogous patch
removes -bound-checking-unique-traps, and allows it to be controlled via
-fno-sanitize-merge=local-bounds.

Most of this patch is simply plumbing through the compiler flags into
the bounds checking pass.

Note: this patch subtly changes -fsanitize-merge (the default) to also
include -fsanitize-merge=local-bounds. This is different from the
previous behavior, where -fsanitize-merge (or the old
-ubsan-unique-traps) did not affect local-bounds (requiring the separate
-bounds-checking-unique-traps). However, we argue that the new behavior
is more intuitive.

Removing -bounds-checking-unique-traps and merging its functionality
into -fsanitize-merge breaks backwards compatibility; we hope that this
is acceptable since '-mllvm -bounds-checking-unique-traps' was an
experimental flag.

This is a step forward to have reporting consistent with other UBSAN
checks.

Runtime and clang parts are here #120515.

https://github.com/llvm/llvm-project/pull/65972 introduced
-ubsan-unique-traps and -bounds-checking-unique-traps, which attach the
function size to the ubsantrap intrinsic.

https://github.com/llvm/llvm-project/pull/117651 changed
ubsan-unique-traps to use nomerge instead of the function size, but did
not update -bounds-checking-unique-traps. This patch adds nomerge to
bounds-checking-unique-traps.

This check is a part of UBSAN, but does not support
verbose output like other UBSAN checks.

This is a step to fix that.