.mergify: Simplify Mergify rules using GitHub status checks

.mergify: Simplify Mergify rules using GitHub status checks

* Enable Mergify queue feature to support auto rebase when
  'push' label is set and gauarntee that all EDK II CI checks
  are run before merging in changes with linear history.
* Use status checks configured in GitHub branch protections
* Allow non EDK II Maintainers to create a PR
  Requires an EDK II Maintainer to accept the change and
  request merge by adding 'push' label.  Only EDK II Maintainers
  have ability to set/clear labels.
* Do not automatically close PRs for personal builds.

Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Sean Brogan <sean.brogan@microsoft.com>
Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Acked-by: Bret Barkelew <bret.barkelew@microsoft.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>