Integrations: perform accessibility audits

Created by: tjkandala

Umbrella issue to centralize discussion. List of open accessibility audit issues: https://github.com/sourcegraph/sourcegraph/issues?q=is%3Aopen+label%3Ateam%2Fintegrations+label%3Awcag%2F2.1+.

Registry:

• #34053 (closed)
• #34052 (closed)
• #34051 (closed)
• #34050 (closed)
• #34049 (closed)

Extensions on file/search pages:

• #34061
• #34060
• #34059
• #34057
• #34056
• #34055 (closed)
• #34054 (closed)

TODO: create and link to umbrella issue for bugs