feat: add `file-saver` plugin

[robingenz]

Current problem

Currently there is no Capacitor 4 compatible plugin that can be used to save files via a dialog.

Preferred solution

Create a Capacitor 4 plugin to save files via a dialog.

Alternative options

No response

Additional context

No response

[stephan-fischer]

@robingenz Its possible with the plugin on ios to save the file on device file system and / or on camera roll? Means:

fileSaver.saveFiles({
    files: [], // bunch of files!
    target: FileSaverTarget.FileSystem
})
//or 
fileSaver.saveMedia({files: []})
fileSaver.saveFiles({files: []})

It is possible to create a branch for this feature and work together on it?

[robingenz]

@stephan-fischer Thank you for your interest! This plugin is currently still on my todo list. Unfortunately there is no ETA. The idea was to let the user select a location via the system file picker where a file from the app should be saved. However, I am not actively working on this plugin yet. Also, new plugins are first released as sponsorware. Therefore PRs are not possible at the beginning, as the development takes place in a different repository.