Context Gas per Function ⛽

[michael-schwarz]

This provides an alternative version of the context gas where it is tracked per function.

• The gas lifter now takes another module that specifies how the gas is handled (allows for further instances)
• The lattice for the gas is now the chain lattice of the actually desired height rather than always having infinite height

I only have two regression tests so far, it would be great if someone else could come up with some more tests before we merge this and run experiments.

Closes #1569

[jerhard]

Looks mostly good, nice capsulation of the Gas internals using the modules! I left some small remarks.

[SchiJoha]

I looked through the changes from the Lifter, and everything looks good :)