Using tokio to complete the rust DoH query implementation

This CL is the complement based on aosp/1531539 by using tokio.
Some implementations are took from aosp/1550834.
This CL would only focus on rust part of DoH.

Using tokio to re-write the event loop and I/O handling.

Test: atest
Bug: 155855709
Change-Id: I5bcc701178358bc442bd8c2af5df03399d7a8137
Merged-In: I5bcc701178358bc442bd8c2af5df03399d7a8137
Ignore-AOSP-First: This CL is merged into aosp. But need to comment out all Rust relevant
build rule as it's not supported here.
(cherry picked from commit f71a7227)