Update httpAdapter: no requirement that a caller use POST

[EvanJRichard]

Summary

This PR just removes the restriction that http rpc callers use POST.

Testing Plan

Poked around in curl, all seems to work fine.

Documentation

Does this change require any updates to the Iron Fish Docs (ex. the RPC API
Reference)? If yes, link a
related documentation pull request for the website.

[ ] Yes
[X] No

Breaking Change

Is this a breaking change? If yes, add notes below on why this is breaking and
what additional work is required, if any.

[ ] Yes
[X] No

[EvanJRichard]

Was just talking this out with @danield9tqh : @NullSoldier , should we gate these to POST and GET, or just generally do no verb restrictions?

[holahula]

How does this work with endpoints that require input parameters? I.e. chain/estimateFeeRate where a priority can be inputted? Are they read from the body of the GET request?

[EvanJRichard]

@holahula yeah, exactly, for example curl -d '{"sequence": 1}' -X GET http://localhost:8021/chain/getBlock works fine