Support IHateMoney QR codes

[magshee]

Closes #90

This required a little more work than I had expected, but I’m really happy to made progress in this PR.

Here are the changes:

• IHateMoney QR codes contain a PROJECT_TOKEN that can be used a as Bearer token for authentication. For some reason, the project identifier was stored in a variable called token. I decided to store the project identifier in a new field and use the token variable for the IHateMoney token.
• I wanted to keep the existing functionality of adding a IHateMoneyProject via project identifier and password. And since Cospend QR codes also still provide these information instead of a project token, I chose to replace the usage of Tupels with actual data types that differ, depending on whether password or access token was used.
• IHM projects can also be added by pasting the invite link via paste button

Thoughts for further consideration:

• Some blocks of code (i.e. in AddProjectQRViewModel were already commented. If they are not used/required, maybe consider removing them
• What is missing is the possibility to create a QR to share a IHateMoney project. This is currently only supported for Cospend projects.
• Do you have any idea, what a MoneyBuster string is? I opened MoneyBuster and shared a project, and got a regular (not masked) project link

Eventually there are still things in here that can be improved, looking forward to your feedback!

[InteractionEngineer]

Thank you very much for the extra effort, I'm happy to see it working now!

Unfortunately, during testing I finally got "the too many requests error" with my own cloud (no matter your new feature changes or my previous attempts to fix #81). I'd like to look into this first before continuing reviewing and testing you changes. A bit tight on capacity right now, but I'll try my best!