feat: Improve mParticle reset methods

[einsteinx2]

Summary

This looks big because of all the test cleanup, but the only real changes are in the mParticle.m/h files and are minimal

• Revert old reset method to it's original implementation and mark it deprecated
• Update new reset: method to use async dispatch to prevent potential for deadlocks

• Clean up tests and ensure use of new reset method

  Testing Plan

• [x] Was this tested locally? If not, explain why.

• All tests pass and performed E2E test to confirm workspace switching still works as expected

  Reference Issue (For mParticle employees only. Ignore if you are an outside contributor)

• Closes https://go.mparticle.com/work/SQDSDKS-6229

[mparticle-automation]

:tada: This PR is included in version 8.21.0 :tada:

The release is available on GitHub release

Your semantic-release bot :package::rocket: