Allow opening a different project

[Cuperino]

Opening a new project closes all files and replaces the current project.

[narnaud]

I see multiple issues here.

On the form:

• there are 2 commits together, one is the close tab that I don't want
• you are not using conventional commit

On the code itself, changing the Project root multiple times is a bit more involved, as project settings are loaded in Project::setRoot.
Also it will require to stop and restart the LSP clients...

I'm not sure it's super important to be able to open multiple projects. If you want to continue in this direction, go ahead, but there's more work than that.
Otherwise close the PR.

[Cuperino]

there are 2 commits together, one is the close tab that I don't want

This was intentional because the changes in feat: allow opening a different project depended on the changes done to the closeDocument function in feat: make document tabs easily closable via mouse. I didn't plan on merging this PR until the one with those changes had been merged.

What I've done here now is duplicate the code in each PR, so they can be merged individually in any order. Whichever PR is to be merged after will have to be re-based and have its conflicts resolved. This isn't a big deal, but it's what I was trying to avoid.

you are not using conventional commit

Fixed.

On the code itself, changing the Project root multiple times is a bit more involved, as project settings are loaded in Project::setRoot.

Fixed by saving settings if settings would've been saved when closing the app, and then reloading all settings in order so everything's anew.

Also it will require to stop and restart the LSP clients...

Done. Tho I'm not sure of how to properly test this...