feat: add option to disable flipper

[mhuynh5757]

Submission Checklist

• [x] The README.md reflects new features
• [x] The CHANGELOG.md reflects any feature, bug fixes, or known issues made in the source code
• [x] New unit tests and integration tests have beed added
• [x] Code coverage is more or equal to the previous coverage
• [x] A visual inspection of the Files changed tab was made prior to submitting the pull request ensuring the style guide was followed
• [x] CI pipeline is green
• [x] Included screenshot if necessary

Description

This PR adds an option during pod install such that you can disable Flipper. It can be used like so

NO_FLIPPER=1 pod install # this will disable flipper

If you want to use Flipper you can pod install as normal

pod install

Breakdown

• Add env var check to the podfile. This change was taken from newer versions of react native podfiles.

Validation

• Ran pod install with and without the flag, Flipper was pulled or not pulled accordingly.

Additional Notes

N/A

Contributing to Twilio

All third-party contributors acknowledge that any contributions they provide will be made under the same open-source license that the open-source project is provided under.

• [x] I acknowledge that all my contributions will be made under the project's license.