Bootstrap proxy for light-node API

[xla]

Introducing a proxy which serves the Tendermint RPC API with the help of a connected RPC client. Later to be extended to add light client functionality. This is in nature equivalent to the Go proxy[0].

Instead of reaching for hyper this change introduces warp to build an HTTP server. This decision should be evaluated very carefully, while warp is a thinly wrapper around hyper, it brings a lot of very important tooling (including Websockets), it also has its own set of dependencies.

Also currently unclear if the module that implements the RPC API with lite client functionality should live in the RPC source tree.

Part of #219

[0] https://github.com/tendermint/tendermint/tree/master/light/proxy

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Still under development, open this draft PR for early feedback and course corrections.

[codecov-commenter]

Codecov Report

Merging #329 into master will increase coverage by 0.6%.
The diff coverage is 19.4%.

@@           Coverage Diff            @@
##           master    #329     +/-   ##
========================================
+ Coverage    28.2%   28.8%   +0.6%     
========================================
  Files         130     131      +1     
  Lines        4880    4975     +95     
  Branches     1511    1561     +50     
========================================
+ Hits         1378    1435     +57     
+ Misses       2533    2500     -33     
- Partials      969    1040     +71     

Impacted Files	Coverage Δ
tendermint/src/rpc/proxy.rs	19.4% <19.4%> (ø)
tendermint/src/net.rs	30.0% <0.0%> (+1.6%)	⬆️
tendermint/src/test.rs	21.0% <0.0%> (+4.3%)	⬆️
tendermint/src/rpc/client.rs	6.0% <0.0%> (+6.0%)	⬆️
tendermint/src/rpc/method.rs	11.3% <0.0%> (+11.3%)	⬆️
tendermint/src/rpc/error.rs	45.9% <0.0%> (+11.7%)	⬆️
tendermint/src/rpc/version.rs	40.9% <0.0%> (+13.6%)	⬆️
tendermint/src/rpc/endpoint/health.rs	25.0% <0.0%> (+25.0%)	⬆️
tendermint/src/rpc/id.rs	86.3% <0.0%> (+27.2%)	⬆️
... and 1 more

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[ebuchman]

Thanks @xla !! But see my comment #219 (comment) - not sure we want to go full proxy yet, probably best to just start with a simple RPC service with two methods and figure out from there how we really want to proceed

[xla]

@ebuchman Read all your comments thoroughly and promise to jump the shark here. Boostraping here means pretty much the two endpoints you mentioned.

[liamsi]

I had to google "jump the shark" and ended up watching this: https://www.youtube.com/watch?v=t4ZGKI8vpcg 😬

This PR, needs to be updated using the new rpc crate: #338

Now that I learned that tendermint (go) actually offers (98%) jsonrpc compatible endpoints, we could use a jsonrpc server crate to expose the endpoints instead.

[xla]

I had to google "jump the shark" and ended up watching this: https://www.youtube.com/watch?v=t4ZGKI8vpcg grimacing

World-class entertainment.

This PR, needs to be updated using the new rpc crate: #338

Think I gonna ditch this one and start fresh on top of #338.

Now that I learned that tendermint (go) actually offers (98%) jsonrpc compatible endpoints, we could use a jsonrpc server crate to expose the endpoints instead.

Agreed!

[xla]

Super-seeded by #363