Add SOCKS5 UDP transport support to aioice

[dayacoder]

• Create comprehensive socks5.py module with complete SOCKS5 implementation
• Add socks5_proxy parameter to Connection class constructor
• Implement SOCKS5 UDP ASSOCIATE protocol according to RFC 1928
• Support both no-auth and username/password authentication
• Add create_socks5_datagram_endpoint for transparent proxy integration
• Include proper error handling and logging for production use
• Support IPv4/IPv6 addresses and domain names

This enables all UDP traffic (STUN, TURN, RTP) to be routed through SOCKS5 proxies for enhanced privacy and network traversal capabilities.

[codecov]

Codecov Report

❌ Patch coverage is 20.64057% with 223 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.29%. Comparing base (29976f5) to head (cf93a3d).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
src/aioice/socks5.py	19.27%	222 Missing ⚠️
src/aioice/ice.py	83.33%	1 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (29976f5) and HEAD (cf93a3d). Click for more details.

HEAD has 16 uploads less than BASE

Flag	BASE (29976f5)	HEAD (cf93a3d)
	30	14

Additional details and impacted files

@@             Coverage Diff              @@
##              main      #98       +/-   ##
============================================
- Coverage   100.00%   85.29%   -14.71%     
============================================
  Files            7        8        +1     
  Lines         1237     1516      +279     
============================================
+ Hits          1237     1293       +56     
- Misses           0      223      +223     

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