Restore "[MemProf] Memprof profile matching and annotation"

This reverts commit 794b7ea9, and
thus restores commit a212d8da, and
follow on fixes 0cd6763f,
e9ff53d4, and
37c6a25e.

Use a hash function (BLAKE3) instead of hash_combine/hash_code which are
not guaranteed to be stable across executions.

Additionally, it adds a "REQUIRES: x86_64-linux" to the tests that have
raw profile inputs to avoid failures on big endian bots.

Reviewers: snehasish, davidxl

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D128142