JetBrains: Replace ⌥+A with a production-ready shortcut for opening the popup

Created by: vdavid

We currently have ⌥A (Alt + A) bound for opening the “Find on Sourcegraph” popup.

⌥A is a premium shortcut, and our use of it might not be justified. As a tester phrased in a user test : “Option-A is a super invasive shortcut that shouldn’t be overridden.”

We could: a.) Leave it as-is (no action) b.) Use a shortcut related to ⌘⇧F (Find in Files). Could be ⌥⇧F or ⌃⇧F (but that'd be Mac only) or ⌘⇧G c.) Use a shortcut using “S” as in Sourcegraph. But that might be a too-busy key already.