wrapcell: Add new command

[povik]

What are the reasons/motivation for this change?

Preserving arithmetic operator boundaries upto a backend tool requires putting them into a module of their own. This module must not be parametric, and should be given a human-readable name (so not the $paramod$... naming used by Yosys internally).

Combinations of techmap -extern, box_derive, chtype can be used for this but the sequencing grows awkward and requires custom techmap files.

Explain how this is achieved.

A new command let's you wrap selected internal cells into individual modules, with the name generated from a template by filling in parameter values.

E.g.

wrapcell -name MUL_{A_WIDTH}_{B_WIDTH}_{Y_WIDTH} t:$mul  # ignores signedness

[widlarizer]

What this PR does currently works ok, but this pattern of log + log_error makes me wish for something like Result types in other languages. Ultimately what we want to do is return from format either a Result(formatted_string) or Error(msg) and if it's Error then return a Error(msg with pass-level context) from execute. This could kind of get it done, but there's no way to match on it, and std::variant is too annoying