MdePkg: Create Google Test mock for MpService Protocol

[v-chhsieh]

Description

This patch creates a gmock for the MpService function, which is used by CI testing.

• Breaking change?
  • Breaking change - Does this PR cause a break in build or boot behavior?
  • Examples: Does it add a new library class or move a module to a different repo.
• Impacts security?
  • Security - Does this PR have a direct security impact?
  • Examples: Crypto algorithm change or buffer overflow fix.
• Includes tests?
  • Tests - Does this PR include any explicit test code?
  • Examples: Unit tests or integration tests.

How This Was Tested

Unit tests component can call these mock functions success.

Integration Instructions

N/A

[shrugupt]

@lgao4 @mdkinney @LiuZhiguang001 Could you please help review this PR.

[lgao4]

I think two commits can be combined into one, and the commit should just describe what is changed, don't need to mention it is used your project.

[v-chhsieh]

I've finished the comment combined.

[shrugupt]

@lgao4 Kindly help review the latest uploaded code changes. Thanks!