[refactor] New top-level app infrastructure, removed AbstractUI, new StorageCore, new Settings UI, and more

Overview

Closes #234 Closes #187 Closes #244

This PR includes the following changes:

The entire top-level app infrastructure has been upended and reimplemented using a new and improved architecture.
- This new architecture is powered by any instance of IModifiableFolder and can be safely multi-instanced, making it easier to extend and maintain.
Rewrote the UI for app settings from the ground up.
- A new "About" page in the Settings view
- A new "Diagnostics" page in the Settings view
- New setup UI for OneDrive and Local Storage.
- The convention for opening the settings UI across every shell has been established. (on Desktop, not mobile).
Removed AbstractUI from StrixMusic.Sdk.CoreModels.
Merged OneDriveCore and LocalFilesCore into a single StorageCore powered by OwlCore.Storage.
Moved audio file scanning code out of the SDK and into the new StorageCore.
Removed Uno from the repo for now. We'll recreate the Uno heads using the latest templates and do an Uno-only bug bash in the future.
Initial IPFS support. Uses OwlCore.Kubo to bootstrap Kubo if IPFS isn't running locally, and can be set up by the user with a single toggle switch.

This PR meets the following requirements:

[x] Tested and contains NO breaking changes or known regressions.
[x] Tested with the upstream branch merged in.
[x] Tests have been added for bug fixes / features (or this option is not applicable)
[x] All new code has been documented (or this option is not applicable)
[x] Headers have been added to all new source files (or this option is not applicable)

Not provided