settings: Added a way to add additional search keywords

[Libadoxon]

Description

This adds a field for both SettingsItem::{Item, Element} to allow additional search aliases for that item. This can be used to either provide more search terms for a field, e.g. having a field titled "Enable Two-factor auth" aliased with "MFA". Another use case is to allow custom elements to provide their own search terms as they don't have/want a title/description.

Screenshot

N/A

How to Test

cargo clippy + verified behavior with example in the settings story

Checklist

• I have read the CONTRIBUTING document and followed the guidelines.
• Reviewed the changes in this PR and confirmed AI generated code (If any) is accurate.
• Passed cargo run for story tests related to the changes.
• Tested macOS, Windows and Linux platforms performance (if the change is platform-specific)

[madcodelife]

I have renamed search_aliases to keywords and added docs.

Thank you!