[Request]: Define custom actions for sharesheet

### Plugin

share_plus

### Use case

It would allow to natively integrate a "create link" feature in _Immich_ without the need to add more screens/ modals.

### Proposal

Starting with Android 14 (API level 34) it is possible to define custom actions, see https://developer.android.com/training/sharing/send#custom-actions.

A new function could be added where the icon, the label, and a listener/ callback function can be defined.

Since only a `Intent.EXTRA_CHOOSER_CUSTOM_ACTIONS` extra has to be added to the share intent, we could define a

I never developed an iOS thus I do not know whether it is possible.