Add to context menu's

[peteruithoven]

In some cases it would be great to access some of the functionality of PDF Tricks directly in applications like Files through the context menu. For example right clicking pdf files and selecting options like "Split PDF" or "Merge PDF".

In elementary OS this can be somewhat easily done by using contract files:
https://github.com/elementary/contractor#writing-contract-files
Of course you'd also need to support command line options to handle this.

I use contract files in my Resizer app:
https://github.com/peteruithoven/resizer/blob/master/data/com.github.peteruithoven.resizer.contract
https://github.com/peteruithoven/resizer/blob/master/data/meson.build#L26-L29