Add matchers field to nest matchers within a rule

[cyamonide]

We want to achieve the following interface:

{
  "name": "foobar",
  "action": "comment",
  "matchers": {
    "includes": ["*.ts"],
    "eventJSONPath": ["foobar"]
  },
  "errorLevel": "foo"
}

to replace the toplevel level matchers (includes, excludes, eventJSONPath, etc.) that existed before.

This will require enhanced JSON guards that can check types inside an object.

[gagoar]

We could also do the same with eventJSONPath and split it into include excludes as well.

{
  "name": "foobar",
  "action": "comment",
  "matchers": {
    "includes": ["*.ts"],
    "eventJSONPath": {
       "includes": ["$.pull_request_body.match('Title')"],
       "excludes": ["$.sender.login.match(/*-bot/)"]
  }
  },
  "errorLevel": "foo"
}