[Github] Hash Pin Actions in Most Workflows (#129486)
This patch haspins all actions in most of the LLVM Github workflows.
This is something we try to do, but no one has gone through and combed
through all of the workflows before this patch.
Notably, this patch does not bump any major versions of actions just in
case there are subtle breaking changes introduced between versions that
could impact us. Also, this patch omits the libc/libc++ workflows so
that they can be split into separate PRs for the respective subproject
maintainers to review.
