Rewrite client and server using reqwest and axum

[ayush-sb]

Pull Request

This PR is to upgrade the network module to hyper 1.1.0.

As mentioned in #1421, hyper 1.1.0 has had many breaking changes. The Client struct no longer exists, and requests are now made by a SendRequest which has a different implementation for HTTP1 and HTTP2. However, this is quite low-level for our needs. Initialization of a SendRequest object also requires a handshake which causes issues like initialization becoming async, resulting in having to make fn default() and other such methods async. Also, some exchanges only support HTTP1, but the HTTP1 SendRequest struct is not cloneable at the moment.

For now, reqwest provides a very similar Client object, with roughly the same functionality. It is also cloneable. Another option is moving to the legacy Client in the hyper-util crate. However, reqwest seems to do the job for now, and we can stay with it until there are some more changes to hyper that make it easier to implement for our needs.

[ayush-sb]

The currently implemented reqwest client passes all existing tests. The next step is to rewrite the test server using hyper 1.1.0 and update all the tests.

[ayush-sb]

The hyper upgrade has also caused breaking changes for servers, such as the removal of Server struct and moving towards a lower-level interface in general. The hyper-util crate also does not provide any legacy Server implementation.

axum provides a simple implementation for servers which is sufficient for our needs. While this is a comparatively heavier dependency, it's kept as a dev dependency as it's only used for tests. Moreover it simplifies the test code a lot. If there are any performance issues down the line, the server can be rewritten using a different crate such as warp or tower-hyper.

[twitu]

Reqwest appears to provide a much cleaner abstraction! Looks good to go 🚀 .