JetBrains: Separate dotcom vs enterprise settings

Created by: vdavid

Fixes https://github.com/sourcegraph/sourcegraph/issues/38575

This is what our Preferences look like now:

This change also fixes the URL-saving bug that Coury encountered yesterday. It was a silly one, basically a typo, and a one-line fix. (You can see it as a separate commit if interested.)

Test plan

Made this 4-min Loom where I demo the UI and the functionality

App preview:

• Web
• Storybook

Check out the client app preview documentation to learn more.