chore(tactic/solve_by_elim): refactor (#2222)
* chore(tactic/solve_by_elim): cleanup
* cleanup
* what happened to my commit?
* fix
* fix
* fixed?
* Tweak comments
* when called with empty lemmas, use the same default set as the interactive tactic
* stop cheating with [] ~ none
* indenting
* docstring
* fix docstrings
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
