Feat: Configuration file

[TGTGamer]

So, I know there's not much that needs configuration files right now, but as configuration options are added. This is going to be crucial :)

If I am using GitButler in my organisation, I want all my colleagues to be able to open the same repo in GitButler and it to work exactly the same out of the box. A Configuration file would achieve this in a easy to implement way.

E.g. #2930
We would want that list of custom bots to ignore to apply to all users on a specific repo, so a simple list of ignored bots in a config file would solve this problem instantly.

Other things people might want to centrally manage:
#2717
#2804
#2870
#2885
#2881

[mtsgrd]

@Qix- would you mind owning this issue since you've got a config file thing in progress?