perf: use Array for CNF formulas

[hargoniX]

• step 1
• step 2.1

[hargoniX]

!bench

[leanprover-radar]

Benchmark results for ee752a7 against 2bca310 are in! @hargoniX

Large changes (2✅)

• ✅ bv_decide_mul//instructions: -5.7G (-12.0%)
• ✅ bv_decide_realworld//instructions: -8.9G (-35.0%)

Medium changes (3✅)

• ✅ build/module/Std.Sat.CNF.RelabelFin//bytes .ilean: -3kiB (-21.4%)
• ✅ build/module/Std.Sat.CNF.RelabelFin//bytes .olean.private: -54kiB (-40.5%)
• ✅ bv_decide_mod//instructions: -13.1G (-5.7%)

Small changes (1✅, 13🟥)

• 🟥 build/module/Std.Sat.AIG.CNF//instructions: +715.8M (+6.1%) (reduced significance based on *//lines)
• 🟥 build/module/Std.Sat.CNF.Basic//bytes .ilean: +5kiB (+28.8%) (reduced significance based on *//lines)
• 🟥 build/module/Std.Sat.CNF.Basic//bytes .olean: +46kiB (+50.6%) (reduced significance based on *//lines)
• 🟥 build/module/Std.Sat.CNF.Basic//bytes .olean.private: +35kiB (+22.7%) (reduced significance based on *//lines)
• 🟥 build/module/Std.Sat.CNF.Basic//bytes .olean.server: +3kiB (+29.2%) (reduced significance based on *//lines)
• 🟥 build/module/Std.Sat.CNF.Basic//instructions: +67.0M (+3.1%) (reduced significance based on *//lines)
• 🟥 build/module/Std.Sat.CNF.Dimacs//bytes .olean.private: +8kiB (+10.9%)
• 🟥 build/module/Std.Sat.CNF.Dimacs//instructions: +24.7M (+2.6%)
• 🟥 build/module/Std.Sat.CNF.Relabel//bytes .ilean: +3kiB (+26.6%) (reduced significance based on *//lines)
• 🟥 build/module/Std.Sat.CNF.Relabel//bytes .olean.private: +15kiB (+13.1%)
• 🟥 build/module/Std.Sat.CNF.RelabelFin//bytes .olean: +11kiB (+20.6%) (reduced significance based on *//lines)
• 🟥 build/module/Std.Sat.CNF.RelabelFin//bytes .olean.server: +800B (+15.5%)
• ✅ build/module/Std.Sat.CNF.RelabelFin//instructions: -536.1M (-35.4%) (reduced significance based on absolute threshold)
• 🟥 build/module/Std.Tactic.BVDecide.LRAT.Internal.Convert//instructions: +2.7G (+142.4%) (reduced significance based on *//lines)