sql/mysql: add AUTO_RANDOM support for TiDB

[negachov]

Add end-to-end support for TiDB's AUTO_RANDOM column attribute, which generates random unique IDs on BIGINT primary key columns to avoid write hotspots.

• Inspect: parse AUTO_RANDOM(shard_bits[, range_bits]) from CREATE TABLE statement, supporting TiDB v5 through v8+ (v8 no longer populates the EXTRA column in
  INFORMATION_SCHEMA)
• Diff: detect addition and parameter changes of AUTO_RANDOM; ignore removal (unsupported by TiDB)
• Migrate: generate AUTO_RANDOM(S) / AUTO_RANDOM(S, R) in CREATE TABLE and ALTER TABLE
• HCL: auto_random (shard bits) and auto_random_range (range bits) attributes with validation and round-trip support
• Normalize RangeBits=64 (TiDB default) to 0 across all paths to prevent spurious diffs
• Add TiDB v8.5.5 to integration test matrix

We are planning to contribute more TiDB-specific improvements. Would it be welcome to send these as incremental PRs?

[Jaakkonen]

This seems to be much better than my #3659 adding this same support in a much more naive way.

[cc-yoshimoto]

@a8m Could you please review this PR? Thanks!

[negachov]

  column "id" {                                                                                                                                                                 
    null        = false                                                                                                                                                         
    type        = bigint                                                                                                                                                        
    auto_random = 5
  }
  ↓
  CREATE TABLE `users` (`id` bigint NOT NULL AUTO_RANDOM(5), `name` varchar(255) NOT NULL, PRIMARY KEY (`id`))

[negachov]

Hi @giautm , could you take a look at this PR when you get a chance? Happy to address any feedback. Thanks!