Filedialog Enhancements

[khoidauminh]

This PR attempts to improve the File Dialog UX by doing the following things:

• Remember the bookmarks in the QT file picker (See FileDialog::FileDialog(...) resets (and overwrites) the Sidebar URLs in LMMS and other QT apps #7405). Any code that modifies the bookmarks have been removed in this PR as this should be left to the user's choice.
• Remember the last opened directory for:
  • Project files
  • Midi files
  • Presets
  • VST plugins
  • Samples
  • Song export
  • Other file types

- [ ] Remember the last opened directories above across different LMMS sessions. I think this won't be needed, and can be implemented later if useful.

[Rossmaxx]

One flaw i could notice was regarding the zyn submodule. Looks like you forgot a recursive submodule update.
So basically, checkout to master, do git submodule update --recursive and checkout back to your branch. Then commit. The submodules should be fixed.

I've been having this thought for some time about using QFileDialog(and other such classes) directly without the inheritance, don't know if it's possible, if possible, that would be the better route. Beyond scope of this PR, but wanted to ask, would it reduce any functionality?

[khoidauminh]

Thanks for the correction!

I've been having this thought for some time about using QFileDialog(and other such classes) directly without the inheritance, don't know if it's possible, if possible, that would be the better route. Beyond scope of this PR, but wanted to ask, would it reduce any functionality?

I think it's possible to drop FileDialog and rework this PR so that no functionality is lost. After all I'm only using FileDialog to encapsulate the OperationPaths code.

[khoidauminh]

I believe this PR is ready for review. (Sorry for the duplicated commits, had a brainfart and messed up my branch)