feat: generate path params definition when missing

[msebastianb]

Generate default param schema only if user doesn't specify a schema for param at all. If there is something, even with missing params, we should not modify it.

Suggested solution

• Check for params in the normalized url and for missing params in schema
• Generate a schema from the params found in the url
• Resolve params to the destination format using the previously generated schema
• Apply this behaviour to both specs

Closes #750

[Eomm]

• Added few minor suggestions
• We need documentation

[simoneb]

@Eomm , @msebastianb won't be able to keep working on this, can you take care of finishing it up?

[mcollina]

lgtm

This seems done to me. What's missing?