chore: support address rate limiting for send raw transaction sync

[danyalprout]

Description
Add sender rate limiting for eth send raw transaction sync requests.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 28.57143% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.34%. Comparing base (9c6ea48) to head (d5df047).

Files with missing lines	Patch %	Lines
proxyd/server.go	28.57%	3 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #488      +/-   ##
==========================================
+ Coverage   59.28%   59.34%   +0.05%     
==========================================
  Files          91       91              
  Lines       12919    12937      +18     
==========================================
+ Hits         7659     7677      +18     
  Misses       4780     4780              
  Partials      480      480              

Flag	Coverage Δ
proxyd	72.06% <28.57%> (+0.11%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
proxyd/server.go	79.54% <28.57%> (-0.08%)	⬇️

... and 2 files with indirect coverage changes

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