core/validatorapi: add eth2wrap logic to proxy

[DiogoSantoss]

Proxied requests from the VC to the BN didn't have our eth2wrap logic (such as sending to multiple BNs or retrying to fallback nodes) neither did they send our additional headers from CHARON_BEACON_NODE_HEADERS.
This changes our proxy to use the eth2wrap client to proxy to (possibly) multiple addresses instead of directly proxing to a single address.

category: feature
ticket: none

[codecov]

Codecov Report

❌ Patch coverage is 57.74648% with 90 lines in your changes missing coverage. Please review.
✅ Project coverage is 53.82%. Comparing base (bba43cd) to head (6350da8).

Files with missing lines	Patch %	Lines
app/eth2wrap/httpwrap.go	61.05%	31 Missing and 6 partials ⚠️
app/eth2wrap/eth2wrap.go	8.00%	23 Missing ⚠️
core/validatorapi/router.go	66.03%	14 Missing and 4 partials ⚠️
app/eth2wrap/multi.go	73.52%	6 Missing and 3 partials ⚠️
app/eth2wrap/lazy.go	50.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4042      +/-   ##
==========================================
+ Coverage   53.80%   53.82%   +0.01%     
==========================================
  Files         242      242              
  Lines       39425    39594     +169     
==========================================
+ Hits        21214    21312      +98     
- Misses      15967    16033      +66     
- Partials     2244     2249       +5     

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[sonarqubecloud]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[pinebit]

Looks like the build is broken