Control viewport framing in camera view

[Pullusb]

Add Reset view within camera (fit viewport)

Can use native fit, but might be better to have a custom fit that consider lateral bars width and add a little margin for a user experience.

Add zoom 1:1 within camera view

Easily set zoom to preview end resolution size (Here just call native operator)

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Those two option can be mapped on the camera swich gizmo button, with shift and ctrl modifiers. Double click can also be considered, but not such a good idea if user wants to quickly chain actions enter cam and lock cam to view.

Since lock cam was added native in 4.1 lock cam button could be viewed as a duplicate, but having those two added features justifies it

[Pullusb]

Need a better default reframe that consider UI overlays for Fit viewport (custom framing)

[Pullusb]

Standby for now. fit view feature is difficult to replicate in python

located on these files in sources for future references:

source/blender/blenkernel/intern/camera.cc
source/blender/editors/space_view3d/view3d_edit.cc
source/blender/makesdna/DNA_camera_types.h

[Pullusb]

Consider this one Done even if it's far from perfect... Might reopen if there is a better fit method in the future.