Providers list constraint violations should not result in a NetworkError

[timcappalli]

In step 2 of https://fedidcg.github.io/FedCM/#browser-api-rp-sign-in, it reads:

If the size of options["identity"]["providers"] is not equal to 1, queue a global task on the DOM manipulation task source given globalObject to throw a new "NetworkError" DOMException

NetworkError doesn't seem appropriate here. I think it should be a TypeError

[npm1]

Yea we have usually used NetworkError for most errors since a lot of them should not be distinguishable from each other. This one in particular would be fine to set as TypeError since it is a 'coding error'. Ideally we'd remove this restriction altogether soon, once we have multi IDP support!