Have render borders moved under Camera settings

Currently in Blender render borders act a bit alike a quick hack.
And they are often indeed used that way.
However a border once set applies to all camera's.
If we need different partial renders of different views or different frames they are not stored.

So re rendering exact the same partial, isnt possible unless it was the last border definition. When working with other people it be handy to be able to re-render a certain area like one did last week for that specific timeline moment.

It would be handy for each camera have its own render border settings, who can be enabled or disabled and as such be different from other camera's. Also it might be handy for artist to be able to enter the exact border window dimensions besides ctrl+h. (ea if one needs something to be specific size).

This is handy for people who work on larger projects. Who create content and are in frequent contact with others artist (or commissionairs) who want changes in models / scenes / characters and are only interested in certain parts.

A more extensive version of this idea would allow for multiple borders per camera, (but i could already live with one per camera (then i would just copy a camera to have other settings, and name a camera accordingly)