Reorganised the Organ Settings dialog as tabbed https://github.com/GrandOrgue/grandorgue/issues/782

[oleg68]

This is a next PR related to #782.

It introduces tabs to the Organ Settings dialog. Now only the Pipes tab exists.

I'm going to add Enclosures tab later.

The behavior of the Organ Settings should not change.

[larspalo]

@oleg68 Whenever I open this (Audio/Midi->Organ settings) dialog I'm now greeted with the message dialog that I need to apply or discard the settings first.

It seems that initially no level in the tree is selected and no values thus are filled.

Note that this happens every single time I open the dialog.

[oleg68]

@larspalo There is no such issue if I build GrandOrgue on ubuntu 22, but if I build it on Ubuntu 20, the issue reappears. I'll do more researching.

[oleg68]

@larspalo I fixed the "apply or discard first"

[oleg68]

@larspalo @rousseldenis could you approve this PR?

[larspalo]

@oleg68 Seems like the latest builds have failed.

[larspalo]

@oleg68 No, sorry, I understand it now. I didn't see that it had a so similar naming to the follow up. I'll test this.

[larspalo]

In all my tests I've not yet found anything more that would oppose this PR.

[oleg68]

@rousseldenis could you approve this PR?