Added fr_fr translation draft

[storca]

Since I'm using this awesome software for a project, I added french translation for the user interface.

I translated what I could, there are still ~50 strings to verify or translate.

[alex-spataru]

Hi! Thanks a lot for the contribution! Just one minor request before merging, is it possible for you to create a "Welcome_FR.txt" file that translates the welcome/startup console messages?

The welcome/startup messages are located in assets/messages folder.

[storca]

Thanks a lot for sharing your project!
Sure! I'll continue to translate the project, I'll also translate the Readme after the UI and welcome text are done, but I'm quite busy 😅

[alex-spataru]

Thanks a lot! No rush at all! It'll be done when it's done, good luck with your work!

[storca]

The UI is mostly done, 2 strings are left to translate, every other string has an equivalent in french but might be innacurate, the french translations are up with fcb1681 (I ran lupdate).
I also translated the welcome message.
Sorry about the multiple commits, I'm still learning...
Oops, I forgot to publish the translation...

[alex-spataru]

Thank you for the translations! Do you want me to merge the changes now, or shall I wait a little longer?

[storca]

I'll fix a typo, release the translation and I think it should be ok
I can't find the french language in the compiled asset here, did I forget something else ?

[alex-spataru]

Hi, sorry for the delay. These last three months where really busy for me (both with thesis & work-related stuff) and I am just getting a two-week break from everything. Can I do anything to help you with this PR?