Refactor local settings to use localization strings

[hjiangsu]

Pull Request Description

This PR adds a way to get a localized string based on a key/string. Flutter does not support mirrors, so this approach is more manual. It requires us to create a map between the key and the localization string. The following changes were made:

• Renamed label to key in LocalSettings enum. This was done because it makes more semantic sense.
• Created an extension on AppLocalizations with a new function getLocalSettingLocalization. This function takes in a key, and outputs the associated localization string.
• Refactored the existing code to handle the new changes

Note: for each new setting we add, we also need to add in the corresponding entry into the map so that it can be associates with the proper localization string.

Reference: https://stackoverflow.com/questions/55445624/how-to-get-a-property-by-this-name-in-string

Issue Being Fixed

This relates to #1036 and hopefully provides a way to allow for localized strings for the search functionality.

Issue Number: N/A

Screenshots / Recordings

Checklist

• Did you update CHANGELOG.md?
• Did you use localized strings where applicable?
• Did you add semanticLabels where applicable for accessibility?

[micahmo]

LGTM!