Add proxy host for extension

[chaudharysaket]

• Add proxy host which can be used by extension https requests
• This implementation is similar to how the New Relic Go agent uses proxy

[codecov]

Codecov Report

❌ Patch coverage is 26.92308% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.70%. Comparing base (45eb888) to head (a140647).

Files with missing lines	Patch %	Lines
telemetry/client.go	26.92%	18 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #338      +/-   ##
==========================================
- Coverage   60.64%   59.70%   -0.94%     
==========================================
  Files          32       32              
  Lines        2927     2951      +24     
==========================================
- Hits         1775     1762      -13     
- Misses       1062     1099      +37     
  Partials       90       90              

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[ashishsinghnr]

Please Add
TLSClientConfig: &tls.Config{
MinVersion: tls.VersionTLS12,
},
So, it will prevents the use of older, vulnerable TLS versions (TLS 1.0, TLS 1.1)