Enable Doppler tracking in Camera3D by default

[Calinou]

This makes setting up AudioStreamPlayer3D with Doppler effect easier.

• Enable doppler preview in the 3D editor viewport by default.
• Move AudioStreamPlayer3D's Doppler Tracking property outside a group since the group only had 1 property, which resulted in unnecessary folding in the inspector.
• Put the AudioStreamPlayer3D Playing and Autoplay properties higher up in the inspector since these are likely to be modified often.

[reduz]

As it is my usual comment on this, enabling it has a base performance cost. Not very expensive though , but if for some reason you instantiate a lot of cameras and dont use them, it can cost significantly.

I generally prefer worse defaults, but a more predictable performance impact.

[Calinou]

As it is my usual comment on this, enabling it has a base performance cost. Not very expensive though , but if for some reason you instantiate a lot of cameras and dont use them, it can cost significantly.

Could we disable doppler tracking for non-current cameras? The current code doesn't seem to take the current state into account.

[ellenhp]

Could we disable doppler tracking for non-current cameras? The current code doesn't seem to take the current state into account.

I don't think this makes sense either. I'd want the doppler tracking information to be ready to go in a camera I'm switching to before I switch to it. The audio code is entirely willing to switch cameras/listeners without waiting a frame first.

Instantiating a lot of cameras is a weird case (plus, an advanced user can simply disable doppler tracking manually on inactive cameras), and I'd be shocked if this is actually a measurable performance issue.

Additionally, I don't think it makes sense to unconditionally enable doppler on current cameras, because a user might wish to have a camera fly over a scene at high speed without having doppler effects. See: #38143 We don't simulate sonic booms, so it will sound weird at extremely high speed.

My preference is to accept this PR.