Codable Settings

[EricBAndrews]

Checklist

• [x] I have read CONTRIBUTING.md
• [x] I have described what this PR contains
• [x] If this PR alters the UI, I have attached pictures/videos
• [x] This PR addresses one or more open issues that were assigned to me:
  • closes #1298
  • closes #1268

Pull Request Information

This PR makes Settings codable. This is accomplished through the intermediate CodableSettings struct; Settings should not be made directly codable because doing so results in AppStorage values being updated every time any Settings object is decoded. CodableSettings ultimately should replace Settings entirely, migrating our settings storage from AppStorage to JSON, but that's OOS here; this means that in the interim we do have the slightly awkward situation of duplicating default values between CodableSettings' decoder and Settings itself.

Some logic has been added to PersistenceRepository to save and retrieve settings files. There are two different locations settings files are stored:

• System: these are app-generated settings files used for migration and persistence. From the code, they are identified by the SystemSetting enum.
• User: these are user-generated settings files. Currently this system is not used, but the idea is to offer easily configurable and swappable settings profiles. These can then optionally be attached to accounts.

The new codable settings enable the following features:

• Migrate from V1 settings
• Save/Restore settings: "Save settings" saves the current settings state to System/v2. "Restore settings" reverts settings to that configuration.
• Import/Export settings: allows users to directly import and export settings JSON files.

To test migration from v1 settings:

• Reset settings state
• Build and launch eric/v1-settings-cache
• Change some settings
• Close the app
• Build and launch this branch

You should see a "Settings Restored" toast and any settings you changed in v1 should be preserved.

[EricBAndrews]

Opened #1323 to handle widget persistence