build: Add docker based building infrastructure

[longfangsong]

Signed-off-by: longfangsong longfangsong@icloud.com

What problem does this PR solve?

Problem Summary:

Building protobuf codes requires so many dependencies and environments (and some of them are not documented), it's too troublesome.

kvproto has already have a docker based building infrastructure, maybe we can have one here too.

What is changed and how it works?

What's Changed:

Add a Dockerfile to create a docker image, which contains all the environment settings we need.

We can use this docker image to do the build work without pain.

How it Works:

See the new readme.md.

[Andrewmatilde]

LGTM

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