feat!: remove nativeFetchMessages (appears deprecated)

[erisu]

Motivation and Context

Remove nativeFetchMessages and fetchCommandsFromJs as it appears to be deprecated.

Description

• Removed fetchCommandsFromJs from CDVCommandQueue.m. Cant find this method called anywhere in our code base.
• Removed execProxy.nativeFetchMessages from exec.js. This method appears to call cordovaExec().nativeFetchMessages which is undefined. It seems to have been removed when UIWebView was dropped in PR: refactor: drop uiwebview & add wkwebview #773

Testing

• npm t
• cordova platform add
• cordova build
• Run default Cordova app in simulator

Checklist

• I've run the tests to see all new and existing tests pass
• I added automated test coverage as appropriate for this change
• Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
• I've updated the documentation if necessary

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.24%. Comparing base (833c7e0) to head (e68c8d1).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1643   +/-   ##
=======================================
  Coverage   80.24%   80.24%           
=======================================
  Files          17       17           
  Lines        5159     5159           
=======================================
  Hits         4140     4140           
  Misses       1019     1019           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.