feat: utility constants and simplified block module

[dave-gray101]

While using gridfinity-rebuilt-openscad in some of my projects, I sometimes find it more readable to use these simple constants to represent some of the fake "enums" like lip_style and gridz_define.

I also use this simple gridfinityBlock wrapper to simplify the creation of subtractive blocks - this is just a simple wrapper around gridfinityInit, height and gridfinityBase functions that creates a "solid bin"

The base_only parameter allows a user to quickly toggle the "upper portion" of the block on and off - this is to easily create a custom mesh to use different slicer settings for the mating surfaces versus the subtractive block.