tools: Fix proto compiler

[thanethomson]

Closes #1014

This also introduces an additional check in CI that (1) generates our protos using our proto-compiler, and (2) tries to build all targets using those generated protos.

• 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 #1015 (71babe8) into master (858b577) will increase coverage by 0.0%.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #1015   +/-   ##
======================================
  Coverage    72.8%   72.8%           
======================================
  Files         206     206           
  Lines       16630   16629    -1     
======================================
  Hits        12114   12114           
+ Misses       4516    4515    -1     

Impacted Files	Coverage Δ
testgen/src/vote.rs	84.7% <0.0%> (-0.9%)	⬇️
light-client/src/types.rs	41.3% <0.0%> (-0.4%)	⬇️
tendermint/src/hash.rs	37.1% <0.0%> (+0.1%)	⬆️
tendermint/src/block/commit_sig.rs	78.0% <0.0%> (+2.0%)	⬆️

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[hu55a1n1]

LGTM! 👌 I can confirm that this fixes #1014. Thanks, Thane!