Fixes #174

Summary
This PR resolves an inconsistency where IPv6 addresses configured via gNMI in uncompressed format were stored as-is in the DB. This behavior broke gnmi_get operations when the same IP was queried in its standard (compressed) form.

Problem Overview
When a user configures an IPv6 address using gNMI, such as:

2001:0db8:abcd:0016::1

…it was stored without compression in the database. This caused:

gnmi_get with compressed IP (2001:db8:abcd:16::1) → fails with “resource not found”

gnmi_get with the exact (uncompressed) configured IP → succeeds

This inconsistency created confusion and prevented retrieval via normalized XPaths.

Root Cause
The IP string from the gNMI request path was used directly in:

Key formation (YangToDb_subintf_ip_addr_key_xfmr)
Configuration merging (YangToDb_intf_ip_addr_xfmr)
No IP normalization was performed.

Fix
We now normalize all IPv6 addresses using:

net.ParseIP(ip).String()
Applied in:

YangToDb_subintf_ip_addr_key_xfmr — for generating consistent keys

YangToDb_intf_ip_addr_xfmr — for normalizing addr.Config.Ip

Testing:

Configured IPv6 address 2001:0db8:abcd:0016::1 via gnmi_set

Verified in Redis that it is stored as 2001:db8:abcd:16::1

Queried via gnmi_get using compressed format → success

Queried via gnmi_get using uncompressed format → fails (as expected)