Perform accessibility audit on IAM & Admin Exp features

Created by: kopancek

@kopancek as our accessibility champion is responsible for performing an accessibility audit on features that our team owns. The result of this audit is a set of github issues created, that we or other teams (and an external company) can tackle. Doing the accessibility audit is a sourcegraph Q2 goal and @kopancek promised to do it until the end of May.

More details on the audit itself are in the slack thread here: https://sourcegraph.slack.com/archives/C038K3PR2M7/p1650964728902099