2023.2: [mono][arm64] Fixed passing/receiving hfa structures with fixed buffers.

[Durengo]

Backport of #1807 for UUM-35682

Fixes dotnet/runtime#90423.

Cherrypicked from upstream. Pick was not clean and required some massaging.

Bug: UUM-30210
Backport: UUM-45433
Trunk PR: #1807

• Should this pull request have release notes?
  • Yes
  • No
• Do these changes need to be back ported?
  • Yes
  • No
• Do these changes need to be upstreamed to mono/mono or dotnet/runtime repositories?
  • Yes
  • No

Reviewers: please consider these questions as well! ❤️

Release notes

Fixed UUM-30210 @Durengo:
Mono: Fixed issue where a fixed buffer within a valuetype struct would not be passed by value correctly.

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