[FEATURE] Configurable solid (internal) infill pattern

[mjonuschat]

Backport of SuperSlicer feature to make the solid (internal) infill configurable. Using alternatives to monotonic/rectilinear for the usually invisible internal infill can be beneficial when printing translucent/transparent materials.

[jschuh]

It looks like #10299 ports the same code. The only functional difference I can see is that this PR applies to solid infill over internal voids, which doesn't seem correct to me since I would assume the bridge infill pattern should be used over voids. Although, maybe I'm just misreading how it works.

[mihaisat]

Hi.I would like a feature that's critical in the final Prusa Slicer 2.6.0 (a feature that's available in SuperSlicer for example so shouldn't be a big issue I guess )
In Hight Range Modifier-> Advanced one of the options should also be Extrusion Multiplier and Temperature too
I print RC planes for LWPLA-HT filament and in order not to be able to detach from the bed it needs to print the first few layers at 100% flow and low temperature and after that at 60% flow and higher temperature.This is the actual suggestion from the filament manufacturer ColorFabb
Anyone can help or can suggest where/how to request this feature ?

[vovodroid]

this PR applies to solid infill over internal voids

No, internal bridge is not changed. Anyway I simplify the code. It seems that currently solid internal pattern is set here https://github.com/prusa3d/PrusaSlicer/blob/master/src/libslic3r/Fill/Fill.cpp#L313, overriding all previous assignments.