[SanitizerBinaryMetadata] Support ignore list

For large projects it will be required to opt out entire subdirectories.
In the absence of fine-grained control over the flags passed via the
build system, introduce -fexperimental-sanitize-metadata-ignorelist=.

The format is identical to other sanitizer ignore lists, and its effect
will be to simply not instrument either functions or entire modules
based on the rules in the ignore list file.

Reviewed By: dvyukov

Differential Revision: https://reviews.llvm.org/D143664