Add validation rule for declaring form parameter and body in OAS 2.0

[AntonKozachuk]

Is your feature request related to a problem? Please describe. Since form parameters are sent in the payload, they cannot be declared together with a body parameter for the same operation - according to the OAS 2.0 docs.

Describe the solution you'd like Need to have a validation rule for this case.

Describe alternatives you've considered n/a

Additional context None.