Consider using the full term `Camera` in `FreeCam`, `PanCam` and friends

[mgi388]

With the new FreeCam and PanCam code introduced in #21520 and #21538, it instantly stood out to me as inconsistent with Camera and Camera3d and also bevy_camera_controller::FreeCamPlugin compared to bevy_camera:::CameraPlugin.

We should work out if we want to change them, or if what we already have is desired.

Original Discord link

[alice-i-cecile]

I would generally like to call these types FooCameraController, and make the plugin names match.

We generally avoid abbreviations to make things easier for non-native speakers. And I think that these types are meaningfully different from e.g. Camera2d, which are about the "type of camera it is", not "how the camera moves" in a way that I would like to signal clearly.

[syszery]

I’ll take a look into this. Also, there’s something else I wanted to check in the PanCam module, so it might be hitting two birds with one stone.