Make selection rectangle correspond to zoom window when respecting ratio

[loichuder]

Fix #1025

I also put the ratio-respecting SelectionRect in its own component. This is a separate commit if you want to read the algorithmic changes first.

As discussed, I could not reuse directly the code in moveCameraTo as it relies on the camera FOV which does not change when drawing rectangles. Instead, I made new utilities to clamp a rectangle in an area.

Given a starting and an end point of a rectangle, the utility will compute the new center of the rectangle so that the rectangle with its actual height/width stays inside the area (the vis in our case). For the selection rectangle, I then compute the shift between the new center and the old one and apply it to the starting and end point. As this is a simple shift, it conserves the ratio of the rectangle.

I could refactor the code in moveCameraTo to make use of the new utilities but I wasn't sure it was worth it.

[axelboc]

Nicely done 👏

[loichuder]

/approve

[axelboc]

Awesome! I think this even opens the door, in a future PR, to let moveCameraTo and clampRectangleToArea accept Vector2 | Vector3.

Only minor thing that bugs me is the naming of clampRectangleToArea, which doesn't fit the return type (Vector2). Perhaps clampPositionToArea would make more sense?