Fix JSON deserialization of abci::ResponseInfo (backport to v0.23.x)

[mzabaluev]

Backport of #1131 to v0.23.x

Should fix informalsystems/hermes#2444

The fields are annotated with json:"omitempty" in the Go source, so give them default values for Deserialize. The /abci_info endpoint is known to omit some of the fields depending on what the node software supplies.

• 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 #1156 (c5e9927) into v0.23.x (ea6fd53) will decrease coverage by 0.0%.
The diff coverage is 0.0%.

@@            Coverage Diff            @@
##           v0.23.x   #1156     +/-   ##
=========================================
- Coverage     67.4%   67.4%   -0.1%     
=========================================
  Files          212     212             
  Lines        20280   20280             
=========================================
- Hits         13680   13677      -3     
- Misses        6600    6603      +3     

Impacted Files	Coverage Δ
testgen/src/apalache.rs	2.6% <0.0%> (ø)
light-client-verifier/src/types.rs	37.9% <0.0%> (-0.9%)	⬇️
testgen/src/header.rs	84.4% <0.0%> (-0.6%)	⬇️
abci/src/server.rs	9.4% <0.0%> (+0.1%)	⬆️

[mzabaluev]

There's been a clippy whack-a-mole in CI, unrelated to the changes in this PR.

[thanethomson]

Thanks @mzabaluev!