feat: Add accessibility collection support to VirtualizedList

[saisreelasyaappali]

This enables Android TalkBack to announce "item X of Y" when navigating through VirtualizedList/FlatList items.

Changes:

• Add AccessibilityCollectionItem type to VirtualizedListProps
• Compute and pass accessibilityCollectionItem to each cell in VirtualizedList
• Apply accessibilityCollectionItem prop on cell wrapper View
• Add accessibilityCollection (rowCount/columnCount) to ScrollView
• Add Flow types for AccessibilityCollection and AccessibilityCollectionItem
• Fix FlatList multi-column grid accessibility with proper row/column indices

Closes #30975

Summary:

This change improves accessibility for VirtualizedList and FlatList by enabling Android TalkBack to correctly announce item position (e.g., "item X of Y") and grid structure. It introduces support for accessibilityCollection and accessibilityCollectionItem, ensuring proper indexing for both single-column and multi-column lists.

Changelog:

[Android] [Added] - Enable TalkBack to announce item position in VirtualizedList and FlatList

Test Plan:

• Verified TalkBack announces "item X of Y" when navigating FlatList items on Android
• Tested both single-column and multi-column FlatList configurations
• Confirmed correct row/column indexing in grid layouts
• Ran existing test suite to ensure no regressions

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