Changed lexers to use Sedlex

[puripuri2100]

Close https://github.com/gfngfn/SATySFi/issues/398

note: dune test has all passed

Reference:

• https://ocaml-community.github.io/sedlex/sedlex/Sedlexing/index.html
• https://docs.mirage.io/menhirLib/MenhirLib/Convert/Simplified/index.html
• https://github.com/unhammer/ocaml_cg_streamparse/blob/master/sedlex_menhir.ml
• https://qiita.com/Tamamu/items/e647c18403681df15c42 (lang:ja)