feat: add 'force_forward' field to request

[cindyyan317]

Clio will forward the request to rippled when 'ledger_index' is 'current' or 'closed'. When 'ledger_index' is 'validated' or other valid number input, there is no way to forward it to rippled.

For purpose of debugging, we allow admin to send request to its p2p rippled with 'force_forward' being true.

[codecov]

Codecov Report

Attention: Patch coverage is 40.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 69.90%. Comparing base (0ede0ed) to head (624632d).
Report is 3 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/rpc/common/impl/ForwardingProxy.hpp	40.00%	0 Missing and 3 partials ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1647      +/-   ##
===========================================
- Coverage    69.91%   69.90%   -0.01%     
===========================================
  Files          260      260              
  Lines         9971     9976       +5     
  Branches      5497     5500       +3     
===========================================
+ Hits          6971     6974       +3     
- Misses        1587     1588       +1     
- Partials      1413     1414       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[godexsoft]

The change looks fine to me 👍 just one style remark 🔢

[godexsoft]

🚀