fix(docs): show version selection dropdown on mobile

[NicholasFlamy]

Description

This change shows the version selection dropdown in the sidebar with the other navbar components on mobile. Before, this wouldn't work correctly. This also required custom CSS to hide the dropdown in the navbar on mobile because Docusaurus wasn't hiding the dropdown in the navbar like it hides the other elements.

How Has This Been Tested?

• Regular desktop loading of localhost dev instance through npm run start
• Inspect Element Dev Console mobile device emulation loading of localhost dev instance through npm run start
• Test the above within the PR preview docs
• Tested again after making the CSS less jank and more future-proof. Also, doesn't need a comment in docs\docusaurus.config.js since changing position shouldn't be a problem.

Screenshots (if appropriate)

Mobile sidebar dropdown:

Mobile navbar properly hiding components with the custom CSS:

Desktop version unaffected (I hovered my mouse over the dropdown for this screenshot):

Checklist:

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation if applicable
• I have no unrelated changes in the PR.
• I have confirmed that any new dependencies are strictly necessary.
• I have written tests for new code (if applicable)
• I have followed naming conventions/patterns in the surrounding code
• All code in src/services uses repositories implementations for database calls, filesystem operations, etc.
• All code in src/repositories/ is pretty basic/simple and does not have any immich specific logic (that belongs in src/services)

[NicholasFlamy]

The one thing I can think of to make this jank a bit safer is to set a custom className to something unique so that the CSS will never apply to the wrong thing.