feat: Track amount of rpc connections

[Exca-DK]

Implements #1512

[codecov[bot]]

Codecov Report

Attention: 25 lines in your changes are missing coverage. Please review.

Comparison is base (e1125b6) 72.76% compared to head (a1a1946) 72.91%. Report is 34 commits behind head on main.

Files	Patch %	Lines
node/metrics.go	60.00%	12 Missing :warning:
jsonrpc/event_listener.go	12.50%	6 Missing and 1 partial :warning:
node/http.go	60.00%	5 Missing and 1 partial :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1520      +/-   ##
==========================================
+ Coverage   72.76%   72.91%   +0.15%     
==========================================
  Files          96       97       +1     
  Lines        9943    10069     +126     
==========================================
+ Hits         7235     7342     +107     
- Misses       2167     2184      +17     
- Partials      541      543       +2     

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