Add custom collection serializer to support object population

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[Copilot]

Pull Request Overview

This PR adds custom collection serializer support to enable object population during deserialization. The changes introduce a new DotvvmCollectionConverter that preserves collection instances during postback updates, preventing unnecessary object recreation.

Key Changes:

• Implemented DotvvmCollectionConverter supporting various collection types (List, Array, ImmutableArray, ImmutableList, etc.)
• Enhanced DotvvmDictionaryConverter with object population capabilities
• Updated property mapping logic to detect and enable population for types with DotVVM converters

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
DotvvmCollectionConverter.cs	New converter implementing collection population for lists, arrays, and immutable collections
DotvvmDictionaryConverter.cs	Enhanced to support populating existing dictionary instances while preserving references
ViewModelSerializationMapper.cs	Added detection of DotVVM converters to enable population for collection properties
ViewModelSerializationMap.cs	Updated dynamic dispatch logic to utilize DotVVM converters for population
DefaultSerializerSettingsProvider.cs	Registered the new DotvvmCollectionConverter
SerializerTests.cs	Added comprehensive test coverage for collection population scenarios

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