rust/xcframework changes to allow firefox-ios to build using spm

[skhamis]

This supports the work going on in mozilla-mobile/firefox-ios#9507 and is needed for allowing full SPM usage and removal of carthage.

Current Hack: SwiftKeychainWrapper had to be bundled with the XCFramework, I made a follow up task to eventually work on this: #4802

Pull Request checklist

• Quality: This PR builds and tests run cleanly
  • Note:
    • For changes that need extra cross-platform testing, consider adding [ci full] to the PR title.
    • If this pull request includes a breaking change, consider cutting a new release after merging.
• Tests: This PR includes thorough tests or an explanation of why it does not
• Changelog: This PR includes a changelog entry in CHANGES_UNRELEASED.md or an explanation of why it does not need one
  • Any breaking changes to Swift or Kotlin binding APIs are noted explicitly
• Dependencies: This PR follows our dependency management guidelines
  • Any new dependencies are accompanied by a summary of the due dilligence applied in selecting them.

[codecov-commenter]

Codecov Report

Merging #4797 (3cc74ae) into main (df53ad8) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #4797   +/-   ##
=======================================
  Coverage   81.53%   81.53%           
=======================================
  Files          49       49           
  Lines        5650     5650           
=======================================
  Hits         4607     4607           
  Misses       1043     1043           

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[tarikeshaq]

LGTM. I didn't review the MZKeyChainWrapper changes, I'm assuming those were just moved over