[VBLOCKS-2088] Update: login and splash screen

[kpchoy]

Submission Checklist

• [ ] The CHANGELOG.md reflects any feature, bug fixes, or known issues made in the source code
• [ ] 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

VBLOCKS-2088

Breakdown

• Add splash screen for ios and android
• update new signin logo
• update twilio logo with higher resolution

Validation

• visual

Additional Notes

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.

[kbagchiGWC]

@kpchoy please add the other PR where the work was done and close this.

[kpchoy]

Done: https://github.com/twilio/twilio-voice-react-native-app/pull/120