meta: Adopt forked prost crates

[xla]

Addresses the lack of a release of the upstream crates for a multitude
of reasons by adopting forked crates on crates.io based off of latest
master. Ideally this is a stop-gap solution until prost itself is
updated properly.

Fixes #966

Signed-off-by: xla self@xla.is

• Referenced an issue explaining the need for the change
• Updated all relevant documentation in docs
• Updated all code comments where relevant
• Wrote tests
• Added entry in .changelog/

[codecov-commenter]

Codecov Report

Merging #1005 (72be665) into master (aee72bd) will decrease coverage by 0.0%.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           master   #1005     +/-   ##
========================================
- Coverage    72.7%   72.7%   -0.1%     
========================================
  Files         204     204             
  Lines       16624   16631      +7     
========================================
+ Hits        12100   12104      +4     
- Misses       4524    4527      +3     

Impacted Files	Coverage Δ
tendermint/src/time.rs	95.7% <ø> (ø)
tendermint/src/signature.rs	56.6% <0.0%> (-4.1%)	⬇️
rpc/src/endpoint/unsubscribe.rs	0.0% <0.0%> (ø)
light-client/src/types.rs	40.8% <0.0%> (+0.3%)	⬆️
testgen/src/header.rs	80.7% <0.0%> (+0.6%)	⬆️
testgen/src/vote.rs	85.5% <0.0%> (+0.8%)	⬆️

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[greg-szabo]

I wonder if releasing a public crate is overkill and we could've maybe gotten away with copying the code into this repo (or maybe as a sub-module). But I'm not the one to argue, let's make this happen.

[thanethomson]

I wonder if releasing a public crate is overkill and we could've maybe gotten away with copying the code into this repo (or maybe as a sub-module). But I'm not the one to argue, let's make this happen.

Adding it as a submodule to tendermint-rs would've probably been far more work than just forking the existing project and republishing the crates under different names. It would've been far easier if we could point our crates to the official Prost repository at a specific commit, but then we wouldn't be able to publish our own crates.

[thanethomson]

Amazing

[tony-iqlusion]

FYI, prost v0.9 is out: https://crates.io/crates/prost/0.9.0