[3.x] Fix multiple issues with CSGPolygon

[madmiraal]

3.x version of #49313.

Note: Although I've marked this as breaks compat, because it changes the way the shapes are created by fixing the way MODE_PATH ROTATION_PATH modes affect extrusion rotations, changes the UV material mappings, reverses the way MODE_PATH normals are defined (i.e. no longer requires them to be inverted see comment), and restricts the valid values for MODE_PATH's path_interval, I still think the quality of the fixes make it viable for 3.4, but the changes would need to be mentioned in the release notes.

[sairam4123]

For my game, I need to have path set to 0.25 for csg mesh to work, but in this case I guess it wouldn't work.

[madmiraal]

Updated to fix bug identified by @stebulba here, and increased the granularity of path_interval in the editor to 0.05 to allow values like 0.25.

[madmiraal]

Updated with suggested changes to the documentation included in #49313.

[akien-mga]

Thanks!