feat(onebot): caching metadata

[nullqwertyuiop]

Receiving: tested on Lagrange.Onebot (aa7ca60)

Known Issue:

1. Selector and ContextClientSelector

   - nick: Nick = await ctx.pull(Nick, ctx.client)
   + nick: Nick = await ctx.pull(Nick, Selector(ctx.client.pattern))

   The type of former is ContextClientSelector while the type of cache keys in context.cache is Selector. When pulling, this line returns None resulting cached metadata not being hit.

2. Undesired results

   This line should return a non-empty badge running in my environment, but in my testing it returns "". According to OneBot 11 Standard Docs it should work in theory but I'm having no other capable implementations. Further tests may be needed.