Smooth Path utils

[ShaMan123]

This PR replaces most of #7082
It focuses on smooth path utils.

Changes:

1. Extracted convertPointsToSVGPath to path util and renamed to getSmoothPathFromPoints
2. Added default correction value to getSmoothPathFromPoints
3. Adapted pencil brush and eraser brush
4. Adjusted tests

[ShaMan123]

Should I add the path builder to this PR?
It is now very simple and minor because of the refactoring + tests.

fabric.Path.pointsToSmoothPath = function (points, options) {
    return new fabric.Path(fabric.util.getSmoothPathFromPoints(points), options);
  };

or fromPointsToSmoothPath

If not I will wait for this to merge

[asturur]

here i am late again!

[asturur]

If we remove that extra if cycle we are good to go with this pr!