rpc: Add temporary fix and tests for block_results serialization

[thanethomson]

Closes #1021

The important changes are in:

• tendermint/src/public_key.rs
• tendermint/src/validator.rs

The reason for the massive line count in this PR:

1. I removed the rpc/tests/support folder and its fixtures, since those were manually generated, in favour of automatically generated fixtures from the rpc-probe (this PR also introduces a small query plan for interacting with a Gaia node).
2. I generated some fixtures from a local Gaia node. These will be replaced when I can get access to the WebSocket endpoint of a production Gaia node.
3. The output of curl http://18.191.147.51:26657/block_results?height=4555980 is added in here as a specific test case to ensure it parses.

One simple way of verifying this code is to check out this branch locally and then, from the root of the repository, run:

# Fetch the block_results response at height 4555980 (previously failed to parse),
# output it to stdout, and pass it through jq for readability.
cargo run -p tendermint-rpc \
    --features cli \
    --bin tendermint-rpc \
    -- \
    -u http://18.191.147.51:26657/ \
    block-results 4555980 | jq

• 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 #1061 (ec10cf9) into v0.23.x (8354fec) will decrease coverage by 0.9%.
The diff coverage is 70.7%.

@@            Coverage Diff            @@
##           v0.23.x   #1061     +/-   ##
=========================================
- Coverage     66.1%   65.1%   -1.0%     
=========================================
  Files          209     210      +1     
  Lines        21023   20744    -279     
=========================================
- Hits         13913   13522    -391     
- Misses        7110    7222    +112     

Impacted Files	Coverage Δ
rpc/src/request.rs	53.5% <0.0%> (-9.0%)	⬇️
tools/rpc-probe/src/common.rs	0.0% <0.0%> (ø)
tendermint/src/public_key.rs	75.0% <72.7%> (-0.1%)	⬇️
rpc/tests/gaia_fixtures.rs	98.4% <98.4%> (ø)
rpc/src/client/transport/mock.rs	88.1% <100.0%> (+<0.1%)	⬆️
rpc/src/client/transport/router.rs	74.5% <100.0%> (+0.4%)	⬆️
rpc/src/client/transport/websocket.rs	64.8% <100.0%> (+0.1%)	⬆️
tendermint/src/validator.rs	73.6% <100.0%> (+1.5%)	⬆️
rpc/src/endpoint/net_info.rs	50.0% <0.0%> (-25.0%)	⬇️
proto/src/serializers/evidence.rs	51.6% <0.0%> (-22.6%)	⬇️
... and 16 more

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[adizere]

Amazing work Thane!

Confirm this works with the provided tests.

One last thought: Would it be worthwhile to make a PR on Hermes pinned with a dependency on this branch, and then pass it to Injective folks for further end-to-end testing? It seems unlikely we can uncover anything with this additional step, but not sure.