Routing and Data Plane improvements

[kalyanpullela]

• Refactor prefix key TrimPrefix to return new key with logging
• Add IP2Me route tracking for proper route removal
• Implement VLAN router interface support
• Add server shutdown handlers (Uninitialize, RemoveSwitch)
• Add streaming notification stubs for standalone mode
• Improve interface stats handling for incomplete forwarding entries

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[sonikajindal]

Can we split this PR into smaller fixes?

[sonikajindal]

/gcbrun

[kalyanpullela]

Can we split this PR into smaller fixes?

Yup, I will close this one and split into about 3 smaller prs.