[VBLOCKS-2074] feat: use initialConnectedTimestamp

[mhuynh5757]

Submission Checklist

• [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
• [ ] CI pipeline is green
• [ ] Included screenshot if necessary

Description

This PR uses the new initialConnectedTimestamp API to persist the call duration between JS runtimes.

Breakdown

• Use new initialConnectedTimestamp API.
• Add new tests.

Validation

• Add new unit tests.
• Manual test on Android and iOS.

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.