Restructure the validation routine and its dependent functions

[kuqin12]

Preface

Please ensure you have read the contribution docs prior to submitting the pull request. In particular, pull request guidelines.

Description

This change removed some redundant code in the validation routine, updated the measurement function interface to return the digest list from measurement operations.

Lastly, the TPM measurement PCR is changed to a fixed at build PCD and default to 17, which will pave way to normal UEFI testing in the upcoming work.

For each item, place an "x" in between [ and ] if true. Example: [x]. (you can also check items in the GitHub UI)

• [x] Impacts functionality?
  • Functionality - Does the change ultimately impact how firmware functions?
  • Examples: Add a new library, publish a new PPI, update an algorithm, ...
• [ ] Impacts security?
  • Security - Does the change have a direct security impact on an application, flow, or firmware?
  • Examples: Crypto algorithm change, buffer overflow fix, parameter validation improvement, ...
• [ ] Breaking change?
  • Breaking change - Will anyone consuming this change experience a break in build or boot behavior?
  • Examples: Add a new library class, move a module to a different repo, call a function in a new library class in a pre-existing module, ...
• [ ] Includes tests?
  • Tests - Does the change include any explicit test code?
  • Examples: Unit tests, integration tests, robot tests, ...
• [ ] Includes documentation?
  • Documentation - Does the change contain explicit documentation additions outside direct code modifications (and comments)?
  • Examples: Update readme file, add feature readme file, link to documentation on an a separate Web page, ...

How This Was Tested

This was tested on QEMU Q35 and verified bootable to UEFI shell.

Integration Instructions

N/A

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

:exclamation: No coverage uploaded for pull request base (feature/spam@faa8e74). Click here to learn what that means.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## feature/spam #288 +/- ## ============================================== Coverage ? 0.46% ============================================== Files ? 144 Lines ? 22349 Branches ? 60 ============================================== Hits ? 105 Misses ? 22239 Partials ? 5 ``` | [Flag](https://app.codecov.io/gh/microsoft/mu_feature_mm_supv/pull/288/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=microsoft) | Coverage Δ | | |---|---|---| | [MmSupervisorPkg](https://app.codecov.io/gh/microsoft/mu_feature_mm_supv/pull/288/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=microsoft) | `0.46% <ø> (?)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=microsoft#carryforward-flags-in-the-pull-request-comment) to find out more.

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