Bug 1657582 - Add nsIDNSResolverInfo interface r=necko-reviewers,geckoview-reviewers,snorp,mixedpuppy,extension-reviewers,dragana

This patch adds the nsIDNSResolverInfo interface which is used to hold
information about the resolver to be used in a DNS resolution.

We use this to merge all of the *WithTRRServer resolve functions into one.
Passing a resolver info will use that object when appropriate. No resolver
info means that we default to using the system resolver, or the default TRR
resolver.

This patch also converts the RESOLVE_TYPE_* flags into a cenum and adds
the resolveType as a parameter to asyncResolve thus removing the need
to have asyncResolveByType methods.

Differential Revision: https://phabricator.services.mozilla.com/D86176