FEATURE: Improve readability of Shift Table headers

[github-actions[bot]]

User Story

• As a Driver or Admin
• I can see that the headers have consistent style
• So that the user experience is better

Discussion

This is what the headers look like currently when viewing the Shifts page

This isn't terrible, but we want to be consistent with the styling across the application and that means capitalization of all headers and multiple words.

So Shift start should be Shift Start, etc.

Acceptance Criteria

• [x] Headers are capitalized

Implementation Todos

Frontend:

• [x] Modify ShiftTable.js to fulfill acceptance criteria

[github-actions[bot]]

Copied from https://github.com/ucsb-cs156/proj-gauchoride/issues/108