[FEATURE] Check order of methods in spec

[dblock]

Is your feature request related to a problem?

Coming from #271 where we reordered a DELETE method.

What solution would you like?

A linter that orders methods (probably GET, POST, PUT, PATCH, DELETE).

What alternatives have you considered?

Alphabetical order.

[nhtruong]

This should be applied to entire spec folder right?
We should also alow --fix option in the linter to auto fix issues like this.

[dblock]

@nhtruong Yes.

[nhtruong]

If someone else is picking this up: We already have a helper function that can do in-place object sorting with a custom priority list.

(Added this previously so I can add custom sorting for operation properties for the linter later. The operations are already following a certain order for their properties. We're just not enforcing it yet.)

[dblock]

We should also alow --fix option in the linter to auto fix issues like this.

#327