Mouse ears style brim

[k1-801]

Is your feature request related to a problem? Please describe.
In some cases, a full brim is not required and may create extra work during post-processing. It could be nice to be able to only print the brim around sharp corners. It is possible to make these manually in CAD, but with large numbers of these corners it may become a complicated task.

Describe the solution you'd like
This video describes it best:
https://youtu.be/MCcFMDv_4eo

(here is a screenshot from the video explaining the idea)

Describe how it would work
Instead of generating a brim following the entire contour of the first layer, this brim generator would only create small circles around sharp edges (i.e. sharp outer turns in the first layers for an angle bigger than specified by a setting, defaulted to 60 degrees). If the circles intersect, they should be processed in the same fashion the bases of organic supports would be. Theoretically, it could just reuse the code for organic support base generation, but instead of center points of the supports it would use the sharp corners.

The code should take into account that the model may contain a fillet of a radius so small that it is essentially a sharp corner, but from the mesh's perspective the lines at the bottom all have small angles between them, so the corner list (probably) can only be processed from semi-final gcode.

UPD: duplicates #10796, #2954, still a wanted feature