feat: added a proxy API to fetch a transaction from the fullnode

[andreabadesso]

Acceptance Criteria

• We should have "proxied" methods for querying the fullnode
• We should have the same global rate limits as we have on our public fullnodes

On using lambdas instead of ApiGateway directly

We could setup the proxy directly on ApiGateway, removing the need for the proxy lambdas (which are currently only making the request and returning the response transparently

That would avoid entirely the lambda calls and decrease our costs

The problem with that approach is that it is currently not supported by the serverless syntax, there is a serverless plugin to configure proxy integrations on the ApiGateway but it does not support HTTP integrations, which would be our usecase

I could try to implement it using the CloudFormation syntax on the serverless file, but it would take some time since I'm not quite used to it and would need some time to study it.

Keeping that and the fact that this API is needed to finish the QA on the wallet-desktop and deploy the wallet-service facade for internal testing, I would suggest deploying the current solution using lambdas and create an issue to refactor this to use ApiGateway directly

Security Checklist

• [X] Make sure you do not include new dependencies in the project unless strictly necessary and do not include dev-dependencies as production ones. More dependencies increase the possibility of one of them being hijacked and affecting us.

[codecov[bot]]

Codecov Report

Merging #361 (06142ea) into dev (f1ddb06) will increase coverage by 0.22%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##              dev     #361      +/-   ##
==========================================
+ Coverage   94.53%   94.75%   +0.22%     
==========================================
  Files          36       37       +1     
  Lines        2251     2308      +57     
  Branches      262      270       +8     
==========================================
+ Hits         2128     2187      +59     
+ Misses        123      121       -2     

Impacted Files	Coverage Δ
src/types.ts	98.59% <ø> (ø)
src/api/fullnodeProxy.ts	100.00% <100.00%> (ø)
src/api/utils.ts	96.42% <100.00%> (+1.69%)	:arrow_up:
src/fullnode.ts	100.00% <100.00%> (+20.00%)	:arrow_up:

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