RangeInteger abstraction for more compact representation

[ehildenb]

This PR seeks to reduce the size of KMIR configurations by packing ranges of integers into a single byte-array instead. Currently, if we ahve a list of Integer(...) of the same unsigned width each, we store it as a List(...) of all the integer instead of packing it into a single Byte array. This leads to way more AST nodes for each term than is needed, and exploded output for the same bytearray.

So this change:

• Detects when we are building a Range of Integer, and instead builds a RangeInteger construct with the bytes packed. It only does this when the integers are byte-aligned, so that the byte-level access we get on bytes are sufficient.
• Updates the semantisc to handle this new RangeInteger construct.
• Adds a testing harness for testing specific lemmas/functional simplifications. This is long overdue, but it adds a way to make direct kprove ... style tests that we can execute for testing lemmas.