Provide better exceptions for errors when building the mapping plan

[jbogard]

This PR adds diagnostic exceptions around mapping individual members. If there's an exception building the expression trees there's not details given from those exceptions.

This covers:

• In memory mapping strategies
  • The type map as a whole
  • Property maps
  • Path maps
  • Constructor maps
• LINQ mapping
  • Property maps
  • Constructor maps

Fixes #4558, #4563

[Copilot]

Pull Request Overview

This PR adds better error handling and diagnostic exceptions when building mapping strategies in AutoMapper. The change wraps critical mapping operations in try-catch blocks to provide more informative exceptions when expression tree building fails.

• Wraps mapping operations in try-catch blocks to catch and re-throw as AutoMapperMappingException
• Adds context-specific error messages for different mapping scenarios
• Covers both in-memory mapping strategies and LINQ projection mapping

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/AutoMapper/TypeMap.cs	Adds exception handling around type map sealing and expression creation
src/AutoMapper/QueryableExtensions/ProjectionBuilder.cs	Adds exception handling for property projections and constructor parameter mapping in LINQ scenarios
src/AutoMapper/Execution/TypeMapPlanBuilder.cs	Adds exception handling for path maps, property maps, and constructor parameter mapping in execution plans

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