[Feature request]: Saving views and switching between them

[mxgrey]

Before proceeding, is there an existing issue or discussion for this?

• I have done a search for similar issues and discussions.

Description

It should be possible for users to save their view into a list. Then users can click on each view in the list to switch the user camera over to that view. The user could also select a default among the views which is what the site editor will use when loading the site.

The list of views would be saved to the site file.

Each view can be associated with a level or can be unassociated. Switching to an associated view will also switch the currently selected level. Switching to an unassociated view will just move the Cartesian coordinates of the camera without changing the current level.

[luca-della-vedova]

Part of this is implemented in #215, specifically the CameraPoses component in camera_poses.rs.
In the PR it will just be initialized from anchors to their baricenter, what will still be missing is the UI to edit the saved camera poses while running.