Audio Capture Subdir

This introduces a new option to the environment config to allow captures to the stored in a subdirectory of the project folder on disk, rather than only in the root.

To go along with that this also cleans up the current confusion in the recording classes around which folder to put stuff in, putting all captures into the capture folder, rather than splitting them between audio captures and video captures, where video captures end up in with the renders. Unless a custom folder is set for audio, then they end up in there with the audio captures.

This is cleaner. Captures all go in the capture folder. And we make the folder if it's pointing to a non-existent folder. This was previously theoretically possible if someone set a custom folder that didn't exist, but that would be a weird thing to do.

Now, though, it's common for people setting subdirs, because each new project will probably not have a capture dir before their first capture.

Also, now that there's two options that require follow-up info, I made it so when you don't have "custom folder" chosen, rather than showing the custom path but having it disabled, I just hide it. And then added another field that shows up to ask the subdir when you've chosen that.

In doing this, I've taken the getProjectFolderName method, which was previously effectively two independent methods toggled by a boolean, and made them two fully different methods.

Closes #1395 (closed)