smtlib2 real/int/fp/bv/bool support

Adds a way to use smtlib2 types in formal proofs, since it would be very nice to use real numbers or fp types and be able to test hardware against them.

Depends on:

• https://github.com/YosysHQ/yosys/pull/3319 -- adds smtlib2_module and smtlib2_comb_expr attributes to yosys that allows custom smtlib2 expressions to be generated by the write_smt2 command.
• https://github.com/YosysHQ/yosys/pull/3391 -- adds hierarchy -smtcheck which acts like -simcheck but allows smtlib2_module blackboxes
• https://github.com/YosysHQ/sby/pull/170 -- switch to using -smtcheck instead of -simcheck when the output is smtlib2, allowing smtlib2_module blackboxes to work.
• https://github.com/YosysHQ/yosys/pull/3357 -- adds cvc5 support to yosys's smtbmc
• !6 (merged) -- fixes all broken tests, needed since it's nice to actually be sure my code didn't break something again.
• !8 (merged)

https://bugs.libre-soc.org/show_bug.cgi?id=835