Implement JSON schema validation

[PeeHaa]

Currently the JSON schema validation is broken and disabled (because broken).

I tried working with opis/json-schema, but I cannot get it to play nice.

Implement JSON validation based on JSON schema. The validation library used must at least support draft-7.

The idea is that plugins can call \AsyncBot\Core\Http::requestJson() with a schema to validate against.

An example of an implementation is done in the IMDB plugin:

• Example schema
• Example of a requestJson call

[mega6382]

I will look into this, I have mostly only done json schema validation in TypeScript(node.js), but I try to see what I can do here. but if someone has more experience with this, then please be sure to step in.