Based on the `ur-registry` upgrade I refactored the `CameraScanner` and `ShowQR` partials: Besides general code changes, the main change is that most of the configuration and result handling now happens on the outer view.
Those partials and functions are now generalized and don't know about their purpose (like handling PSBTs): They can be instantiated with simple data (e.g. for displaying a plain QR code) or different modes (like showing a static and the UR version of a QR code) and the result handling is done via callback.
The callbacks can now also distinguish between the different results (data as plain string vs. UR-type objects for wallet data or PSBT) and also handle the specific type of data. For instance: Before it wasn't possible to strip the leading derivation path from an xpub when scanning the QR code, because the scanner didn't know about the type of data it was handling. Now that the data is handled in the callback, we can implement that functionality for the scan view only.
* Move TagHelpers to Abstractions
Makes them available for use in plugins. Also cleans up the tag helper references in the view code: As we have it in the root view imports, the individual directives in the views are superfluous.
* Move CurrenciesSuggestionsTagHelper back
To get rid of the Rating dependency in Abstractions.
