Address accessibility concerns with new drawer for Requirements creation and edit form

There are a couple issues currently regarding accessibility when it comes to the new drawer that was implemented in !37943 (merged) for Requirement creation/editing. One is that the focus states for the buttons within the form are not displaying, and the second is that users are able to tab focus to elements that are hidden by the drawer, which can be resolved with a keyboard trap.

Issues to address:

• Fix focus state on buttons for Requirement creation/edit form Fixed in !38422 (merged)
• Modify so when the drawer is open, the keyboard focus is trapped within the drawer until the drawer is closed (example here) Fixed in !48325 (merged)

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