consolidate all resolution in resolver; split units

src/admin/debug/commands.rs

src/admin/query/resolver.rs

src/service/client/mod.rs

src/service/resolver/actual.rs

src/service/resolver/cache.rs

src/service/resolver/dns.rs

src/service/resolver/fed.rs

src/service/resolver/mod.rs

src/service/resolver/tests.rs

src/service/sending/mod.rs

src/service/sending/send.rs