github actions: Make Builds on Merge Request Work

Since we need to make sure external contributors code actually compiles
prior to merging. To get access to the forked repos merge request we
need to switch over our push/pull_request to pull_request_target.  In
addition we're fixing up some Naming Conventions, adding aarch64 to this
branch and fixing the naming so that we can quickly identify if the CI
is for x86_64 or aarch64.

Removes pull request checker it is being rewritten and doesn't work as
intented for fork merges.

Author: PlaidCat