Almost Unify Everything

See changes until https://git.karmakrafts.dev/kk/mc-projects/almost-unify-everything/-/tree/d7b347fcf59d760356c8c89134fa9080d726421e

See changes until https://git.karmakrafts.dev/kk/mc-projects/almost-unify-everything/-/tree/0bbfe099ea3a439ae4fe1c5062ad9bdae0822117

• Added progress indication for block entity unification
• Filter out non-existant chunks when unifying block entities

• Added versions.json for update checking

• Added /unifyeverything unify all