PrmPkg/Test/UnitTest/Library: Add initial UEFI Boot Services test lib

Adds a host-based specific implementation of UefiBootServicesTableLib.
This library implements relatively simple versions of the functionality
in the actual boot services implementation and does not depend on
dynamic linking to the boot services table.

Most unit tests can install the dependencies their code under test
depends on prior to invocation and uninstall those dependencies after
the test to test code that directly depends on boot services.

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>

PrmPkg/Test/UnitTest/Library/UefiBootServicesTableLibUnitTest/UefiBootServicesTableLibUnitTestTpl.c

@@ -0,0 +1,43 @@
+/** @file
+  Implementation of Task Priority Level (TPL) related services in the UEFI Boot Services table for use in unit tests.
+
+Copyright (c) Microsoft Corporation
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include "UefiBootServicesTableLibUnitTest.h"
+
+/**
+  Raise the task priority level to the new level.
+  High level is implemented by disabling processor interrupts.
+
+  @param  NewTpl  New task priority level
+
+  @return The previous task priority level
+
+**/
+EFI_TPL
+EFIAPI
+UnitTestRaiseTpl (
+  IN EFI_TPL      NewTpl
+  )
+{
+  return TPL_APPLICATION;
+}
+
+/**
+  Lowers the task priority to the previous value.   If the new
+  priority unmasks events at a higher priority, they are dispatched.
+
+  @param  NewTpl  New, lower, task priority
+
+**/
+VOID
+EFIAPI
+UnitTestRestoreTpl (
+  IN EFI_TPL NewTpl
+  )
+{
+  return;
+}