Consolidate boards into one Vue app

What does this MR do and why?

Removes use of HAML search_bar in Issue and Epic boards.

Consolidates Vue components. Migrates non dynamic props to use provide/inject.

No visual or behavioural changes, this is a refactor.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #355130 (closed)