.azurepipelines: Add Azure Pipelines YML configuration files

https://bugzilla.tianocore.org/show_bug.cgi?id=2315

Add YML configuration files used to run the EDK II Continuous
Integration (CI) checks on Azure Pipelines agents.

Cc: Sean Brogan <sean.brogan@microsoft.com>
Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>
Cc: Liming Gao <liming.gao@intel.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

.azurepipelines/Ubuntu-GCC5.yml

@@ -0,0 +1,18 @@
+## @file
+# Azure Pipeline build file for a build using ubuntu and GCC5
+#
+# Copyright (c) Microsoft Corporation.
+# SPDX-License-Identifier: BSD-2-Clause-Patent
+##
+trigger:
+- master
+pr:
+- master
+
+jobs:
+- template: templates/pr-gate-build-job.yml
+  parameters:
+    tool_chain_tag: 'GCC5'
+    vm_image: 'ubuntu-latest'
+    arch_list: "IA32,X64,ARM,AARCH64"
+