feat: implement getsockname() #72

[suryaprakash0010]

This PR implements the missing getsockname() function.

Changes:

• Added getsockname() to LibOS interface
• Implemented support in SharedNetworkQueue to retrieve local socket address
• Updated demi_getsockname() C binding with validation, buffer checks, and error handling
• Ensured consistency with existing getpeername() implementation

Key Points:

• Memory safety ensured with proper pointer and buffer handling
• Error handling follows Demikernel conventions (EINVAL, ENOTCONN, ENOTSUP)
• Supports IPv4 (consistent with current design)
• Includes debug tracing for troubleshooting

Fixes #72

[suryaprakash0010]

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