[ZhuchkaTriplesix]

Closes #1571

• RedisReply (core/database/redis_reply.dart): RedisNil, RedisInt, RedisSimple, RedisBulk, RedisArray, RedisErrorReply, parsed once from what the redis package returns. asInt(), asArray(), asBulk(), asText(), asDouble(), asBulkOrNull() throw RedisProtocolException on a wrong shape, where redisReplyInt(reply, -1) turned it into a number.
• RedisConnection.command(List<Object>) returns a RedisReply. Arguments are String | int | double | Uint8List | RedisBulkValue, converted in one place; anything else is an ArgumentError before it reaches the wire. sendCommand stays as the raw call for the CLI terminal and the fakes.
• The readers (scan, getMaxDatabases, keyType, ttl, typesAndTtls, get, hgetall, hscan, lrange, lindex, smembers, sscan, zrangeWithScores, the length and del counts, exists, renamenx, delMany) use it; the nine hand-written is List / length == 2 checks are two small helpers (_cursorAndBulks, _pairs).
• RedisConnectionTestFake (~280 lines that shipped in the release binary) is now test/support/redis_connection_test_fake.dart; nine test files import it from there. redis_connection.dart went from 1162 to 848 lines.

Behaviour: the same for a real server. What changes is a reply of the wrong shape: it now throws instead of becoming 0, -1 or an empty list. The existing Redis, database, nosql, workspace and e2e tests pass unchanged (1262 locally), so the fakes already answered in the right shapes.

Tests: redis_reply_test.dart (what RedisReply.from makes of each raw reply, accessors, the exception, non-UTF-8 bytes, command argument conversion and refusal).