Add exception routes configuration to html validator

[Autre31415]

Right now we can selectively disable the validator on specific routes via header values or model values, but in some cases it would also be useful to allow the validator to be disabled on a route by route basis, or more broadly via a route prefix.

A specific scenario where this can come up is when utilizing a module that dynamically generates data API routes in a way we can't fully interact with; it would be ideal to have a convenient way to exempt a series of routes based on a prefix to get around it.