Remove in tree asio deps

[c8ef]

Why

Currently, we rely on the in-tree asio, which makes it difficult to upgrade versions.

What is changing

• Remove the tree in asio. -> 4241e21
• Update bazel builds; update demo-example to accommodate new asio changes. -> f23ac9c
• Update cmake builds. -> e172f66

Example

[ChuanqiXu9]

I still like in-tree deps as it is only for examples. And many people have some problems with network, so I don't want to change this. If you want to upgrade its version, I think you can upgrade it too. It might not be so hard.

[c8ef]

I still like in-tree deps as it is only for examples. And many people have some problems with network, so I don't want to change this. If you want to upgrade its version, I think you can upgrade it too. It might not be so hard.

I agree with the network conditions, but we have been using this approach for gtest for two years. I simply copied the approach.

async_simple/cmake/FindGTest.cmake

Lines 10 to 15 in ddbd887

	FetchContent_Declare(
	googletest
	GIT_REPOSITORY https://github.com/google/googletest.git
	GIT_TAG v1.17.0
	GIT_SHALLOW ON
	)

If users find it difficult to clone the repository, using asio from the package manager would be a better solution. And the newly added cmake file supports this.

[ChuanqiXu9]

Sounds not bad