Resolve "Bump raft-rs to 0.7.0"

Summary

Major change of raft-rs 0-7-0: Support fetch raft entry in async way Though in this MR we are not adding any support for async raft entry processing.

Issue with protoc version has been solved, for details see #369 (closed)

• Close #369 (closed)
• Cherry-pick to: none
• See also: https://github.com/tikv/raft-rs/releases/tag/v0.7.0

Closes #369 (closed)