SignedCapsulePkg: Add package CI YAML file

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=4050

Adds the package as a supported package to .pytool/CISettings.py
and adds a CI YAML for the package so it can be run in CI.

Cc: Jian J Wang <jian.j.wang@intel.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>

.pytool/CISettings.py

@@ -65,6 +65,7 @@ class Settings(CiBuildSettingsManager, UpdateSettingsManager, SetupSettingsManag
                 "UefiCpuPkg",
                 "FmpDevicePkg",
                 "ShellPkg",
+                "SignedCapsulePkg",
                 "StandaloneMmPkg",
                 "FatPkg",
                 "CryptoPkg",