storage, encoded ops: add dictionary encoding infrastructure + encoded operations (Phases 1-4)#1

devin-ai-integration[bot] wants to merge 3 commits into

tidb-shard-key-support-v8.5.66si/tiflash:tidb-shard-key-support-v8.5.6from

tidb-encoded-support-v8.5.66si/tiflash:tidb-encoded-support-v8.5.6Copy head branch name to clipboard