Refactor Tab Bar to abstract styles away from logic

[austincondiff]

Description

This PR attempts to refactor the tab bar to abstract styles away from logic allowing us to easily create and swap out tab styles. It also reorganizes and splits up files so that they aren't so long and easier to read/maintain.

Related Issues

• closes #1207

Checklist

• [x] Remove tabs from TabBarView and added them to a new file called TabBarTabs.
• [ ] Remove leading accessories from TabBarView and added them to a new file called TabBarLeadingAccessories.
• [ ] Remove trailing accessories from TabBarView and added them to a new file called TabBarTrailingAccessories.
• [ ] Separate tab bar styles from logic
• [x] I read and understood the contributing guide as well as the code of conduct
• [x] The issues this PR addresses are related to each other
• [ ] My changes generate no new warnings
• [ ] My code builds and runs on my machine
• [ ] My changes are all related to the related issue above
• [ ] I documented my code

Screenshots

No visual changes should occur due to this PR.