Build-in rule to detect schemas with type mismatch

[tatomyr]

Is your feature request related to a problem? Please describe.

It's possible to define schemas of type object that contain the items field and vice versa. Such schemas don't make sense.

Describe the solution you'd like

We need to add one more built-in rule that shows a warning for this case.

Describe alternatives you've considered

Doing nothing.

[jeremyfiel]

these rules already exist thanks to Adam.

Redocly/redocly-cli-cookbook#33

[tatomyr]

@jeremyfiel yes, but we can do that better with a built-in rule. I expect to add more cases to this rule later on.