fix(a11y): Replace Collapse and Button with Accordion components in PlanningConstraints

[DafyddLlyr]

What does this PR do?

• Replaces the combination of Button and Collapse components with an Accordion component
• Moves some Accordion theming to the MUI theme so that there's more consistency with our other accordions (currently just ResultReason)
• No intentional visual changes
  • Apart from one!
  • The colour for the Caret and hover is now fixed and not based on primary colour - I wasn't sure if this was intentional in the first place, or a hangover from using a Button.
  • If you could take a look at this one please @ianjon3s and confirm that would be much appreciated! 🙌

	Before	After
Screenshot
Link	Storybook (Prod)	Storybook (Pizza)

Motivation

• Suggested by accessibility report (page 19)
• Removes boilerplate code for managing collapsed/expanded state
• Handles accessibility properties natively (e.g. expanded, aria-controls)
  • Docs: https://mui.com/material-ui/react-accordion/#accessibility

[DafyddLlyr]

Verbose, but it resolves this issue -

[github-actions]

Removed vultr server and associated DNS entries

[DafyddLlyr]

List structure [A]

[ianjon3s]

A few small comments on the diffs relating to ID usage and styling parity.

Really good to see this updated to the appropriate accordion component!

[DafyddLlyr]

Thanks @ianjon3s - some great catches there. All three issues should be fixed by 11c24aa