abci: Change hashes' type from Bytes to tendermint::Hash or tendermint::AppHash

[mzabaluev]

Fixes: #1095

Both questions in #1095 (comment) are resolved with "Yes".

• 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/

[mzabaluev]

Mysteriously, this is serialized as an array of bytes rather than a hex string.
This PR does not change it.

[codecov-commenter]

Codecov Report

Merging #1232 (8c5565b) into main (d102af4) will increase coverage by 0.0%.
The diff coverage is 77.1%.

@@          Coverage Diff          @@
##            main   #1232   +/-   ##
=====================================
  Coverage   64.2%   64.3%           
=====================================
  Files        244     244           
  Lines      21364   21373    +9     
=====================================
+ Hits       13734   13746   +12     
+ Misses      7630    7627    -3     

Impacted Files	Coverage Δ
tendermint/src/abci/request/offer_snapshot.rs	0.0% <0.0%> (ø)
tendermint/src/abci/response/init_chain.rs	0.0% <0.0%> (ø)
tendermint/src/genesis.rs	100.0% <ø> (ø)
tendermint/src/abci/response/info.rs	50.0% <50.0%> (ø)
tendermint/src/hash.rs	63.0% <76.9%> (-0.6%)	⬇️
rpc/tests/kvstore_fixtures.rs	98.2% <100.0%> (+<0.1%)	⬆️
testgen/src/vote.rs	84.8% <0.0%> (-0.9%)	⬇️
testgen/src/header.rs	83.5% <0.0%> (-0.6%)	⬇️
tendermint/src/node.rs	63.8% <0.0%> (-0.2%)	⬇️
light-client-verifier/src/types.rs	39.3% <0.0%> (+0.5%)	⬆️
... and 1 more

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[thanethomson]

I think this makes sense. And for the record, my answer to both questions in #1095 (comment) is yes.