Rebuild the client around connections, transports and commands

[scothis]

Replace the store interface and the ops component with a
componentized:valkey@0.3.0-dev package that separates the mechanics of
a connection from the transport carrying it, and from the commands sent
over it. Connections always speak RESP3.

• connection: pairs commands with replies, keeps push messages apart,
  re-establishes state after RESET, and advertises the client's name and
  version. Pub/sub, transactions and WATCH are part of the connection,
  with a subscription resource for channels, patterns and shard
  channels. connection-minimal is the same interface without pub/sub,
  for a smaller component.
• tcp and tcp-connector: connections over wasi:sockets to the server.
  The connector defines a no-arg method to establish a pre-configured (via
  wasi:config) connection.
• commands: typed functions for Valkey's command set, following
  Valkey's command definitions, with the shared types in a types
  interface. Values are string, bytes or string-or-bytes, so
  binary data round trips.
• componentized-valkey crate: the types, the RESP codec and the
  conversions between commands, replies and the WIT types, shared by
  the components.

Network access can be limited with componentized:sockets gates.
tcp-connector-latch allows only the server in the connector's config
(its hostname, by name or IP address, on its port, over TCP) and denies
every other socket. The cli is always behind a gate with this latch,
composed so that components behind the gate cannot import wasi:sockets
around it.

Tests run components in wasmtime with a shared harness. Guest-side
suites cover the commands and the latch, the latch over stub sockets so
that denials are certain. make test-valkey runs the integration tests
against Valkey in a Docker container.