[FEATURE] Add support for web and search result citations in Bedrock

[danilop]

Is your feature request related to a problem?

The Bedrock Converse API supports multiple citation location types, but the SDK currently only handles document-based citations (documentChar, documentPage, documentChunk). Web-based citations and search result citations are not supported.

Describe the solution you would like

Add support for:

• WebLocation - citations from web sources with url and domain fields
• SearchResultLocation - citations from search results with searchResultIndex, start, and end fields

This enables features like Nova Web Grounding to return properly typed citations.

Describe alternatives you have considered

N/A - this is required for complete API coverage.

Additional context

• Related to [FEATURE] Add support for system tool #1154 (system tool / Nova Web Grounding support)
• Depends on [BUG] Bedrock Runtime API CitationLocation Tagged Union Structure Error #1323 being fixed first (CitationLocation tagged union structure)
• API Reference: https://docs.aws.amazon.com/bedrock/latest/APIReference/API_runtime_CitationLocation.html