Add WebSocketClient::new_with_config to specify the WebSocket connection settings

[romac]

Closes: #974

This PR directly re-exports the tungstenite::protocol::WebSocketConfig. We could also define our own config type and convert it into the former if that's deemed preferable.

• 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/

[thanethomson]

Looks great! Just a changelog entry and these minor tweaks and I think we're good to go here.

[codecov-commenter]

Codecov Report

Merging #975 (11a0b75) into master (80559bd) will increase coverage by 0.0%.
The diff coverage is 66.2%.

❗ Current head 11a0b75 differs from pull request most recent head d617af7. Consider uploading reports for the commit d617af7 to get more accurate results

@@          Coverage Diff           @@
##           master    #975   +/-   ##
======================================
  Coverage    72.1%   72.2%           
======================================
  Files         203     204    +1     
  Lines       16577   16621   +44     
======================================
+ Hits        11961   12006   +45     
+ Misses       4616    4615    -1     

Impacted Files	Coverage Δ
light-client/examples/light_client.rs	0.0% <0.0%> (ø)
rpc/src/client.rs	16.9% <ø> (ø)
rpc/src/client/bin/main.rs	0.6% <0.0%> (-0.1%)	⬇️
rpc/src/lib.rs	100.0% <ø> (ø)
rpc/src/endpoint/consensus_params.rs	40.0% <40.0%> (ø)
rpc/src/method.rs	29.5% <50.0%> (+<0.1%)	⬆️
rpc/src/client/transport/websocket.rs	63.8% <66.6%> (+0.9%)	⬆️
rpc/tests/kvstore_fixtures.rs	95.4% <100.0%> (+<0.1%)	⬆️
rpc/src/endpoint/validators.rs	20.0% <0.0%> (-30.0%)	⬇️
rpc/src/endpoint/net_info.rs	75.0% <0.0%> (-25.0%)	⬇️
... and 14 more

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