PrmPkg: Changes for edk2 repo transition

Updates the Readme.md files to remove information that was specific
to the package in edk2-staging and adds key definitions being added
for PRM support in the ACPI Specification.

Adds PrmPkg/PrmPkg.ci.yaml to support CI.

Adds PrmPkg to .pytool/CISettings.py.

Adds PrmPkg maintainers to Maintainers.txt.

Cc: Andrew Fish <afish@apple.com>
Cc: Kang Gao <kang.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Michael Kubacki <michael.kubacki@microsoft.com>
Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Benjamin You <benjamin.you@intel.com>
Cc: Liu Yun <yun.y.liu@intel.com>
Cc: Ankit Sinha <ankit.sinha@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Acked-by: Michael D Kinney <michael.d.kinney@intel.com>
Acked-by: Liming Gao <gaoliming@byosoft.com.cn>
Acked-by: Leif Lindholm <quic_llindhol@quicinc.com>
Reviewed-by: Ankit Sinha <ankit.sinha@intel.com>

.azurepipelines/templates/pr-gate-build-job.yml

@@ -37,7 +37,7 @@ jobs:
         Build.Pkgs: 'NetworkPkg,RedfishPkg'
         Build.Targets: 'DEBUG,RELEASE,NO-TARGET'
       TARGET_OTHER:
-        Build.Pkgs: 'PcAtChipsetPkg,ShellPkg,StandaloneMmPkg'
+        Build.Pkgs: 'PcAtChipsetPkg,PrmPkg,ShellPkg,StandaloneMmPkg'
         Build.Targets: 'DEBUG,RELEASE,NO-TARGET'
       TARGET_FMP_FAT_TEST:
         Build.Pkgs: 'FmpDevicePkg,FatPkg,UnitTestFrameworkPkg,DynamicTablesPkg'