[DPG] do not generate maxpagesize on client operations

[kristapratico]

According to @johanste, this parameter should not be accessible at the client operation-level. We should instead accept this kwarg on the ItemPaged.by_page().

[johanste]

Correctamundo. I think that it should be a safe assumption that any parameter that matches maxpagesize (with or without a leading '$' sign, and case insensitive) should be folded into the pageable code generation.

[johanste]

On a related note, @iscai-msft, are morphing conditional requests (e.g. if-match and friends) into the corresponding well-known parameters in our DPG code gen?

[iscai-msft]

Sorry I don't quite get your last question. If your last question is "are we special casing any parameters into well-known locations", we aren't really right now

[johanste]

We should be. In the fullness of time. In the short term, we can do swagger transforms. But we want to make things go on autopilot/not needing any human intervention for these kind of things.