Shortcut Activity (ACTION_CREATE_SHORTCUT manifest intent-filter)

### ⚠️ This issue respects the following points: ⚠️

- [X] This is a **enhancement/feature request**. Not a [bug or question](https://github.com/gsantner/markor/issues/new/choose).
- [X] The topic is **not** already reported at [Issues](https://github.com/gsantner/markor/issues?q=#js-issues-search). _(I've searched it)_.
- [X] Markor **is** up to date. See [Releases](https://github.com/gsantner/markor/tags) for the latest version. Updates are available from [F-Droid](https://f-droid.org/en/packages/net.gsantner.markor/) and GitHub.
- [X] The wanted feature/enhancement is not present in the latest development version (git master). (Please [download](https://nightly.link/gsantner/markor/workflows/build-android-project/master) and try the test version of Markor, named **Marder**. Don't worry; Markor and Marder appear as completely separate applications. You can install both side-by-side, and Markor's settings are not touched. If your desired feature is present, you don't need to open this issue. The change will be part of the next Markor update.)

### Description

Note: This is not about the app's launcher icon but actually the existing feature inside Markor of "Create shortcut" to immediately open a file with one tap.

There are at least two ways to add a shortcut in Android:

1. **Through the app**: like what Markor currently does. But it adds the shortcut to the default launcher/home screen only.
2. **Through the launcher**: the same as a widget. You long press on the home screen and choose add shortcut. Then you are presented with the different shortcut creating dialogues/activities declared by the apps in the manifest. This is the only way to add a shortcut to a non-default launcher.

[This should be simple enough](https://developer.android.com/develop/ui/views/launch/shortcuts/creating-shortcuts#custom-pinned) and allows creating a shortcut in assistants and non-default launchers (like these: [1](https://play.google.com/store/apps/details?id=com.dynamicg.homebuttonlauncher), [2](https://play.google.com/store/apps/details?id=com.appindustry.everywherelauncher), [3](https://play.google.com/store/apps/details?id=fr.neamar.kiss)).

Side launchers are very helpful, so I would really like it if you considered this small addition.

Thanks

### Information

Android version: 13
App version: 2.11.1

### Source

F-Droid