Improve assertions error messages with structured format

[Evangelink]

Fix #7421

[Copilot]

Pull request overview

This pull request modernizes assertion error messages by introducing a structured, multi-line format that improves readability and developer experience. The changes replace old-style concatenated messages with formatted parameter displays using raw string literals.

Changes:

• Introduced structured error message formatting with parameter names, expressions, and values on separate lines
• Added helper methods for value formatting, expression truncation, and redundancy detection
• Updated all assertion methods to use the new formatting approach
• Removed obsolete resource strings and added new simplified ones
• Updated all test expectations to match the new message format

Reviewed changes

Copilot reviewed 41 out of 41 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
Assert.cs	Core formatting infrastructure: FormatValue, FormatParameter, truncation logic
Assert.ThrowsException.cs	Updated to new structured format for exception type mismatches
Assert.StartsWith/EndsWith/Matches.cs	String assertion methods using new format
Assert.IsTrue/IsFalse.cs	Boolean assertion methods with condition parameter display
Assert.IsNull/IsNotNull.cs	Null checking assertions with value display
Assert.IsInstanceOfType/IsExactInstanceOfType.cs	Type checking with structured type comparison
Assert.IComparable.cs	Comparison assertions (greater/less than, positive/negative)
Assert.Count/Contains.cs	Collection assertions with expression parameters
Assert.AreSame.cs	Reference equality with hash code display for disambiguation
FrameworkMessages.resx	Resource string simplification and new message keys
xlf files	Localization files marked with untranslated entries
Test files	Updated expectations for all assertion error messages

[Copilot]

Pull request overview

Copilot reviewed 44 out of 44 changed files in this pull request and generated 7 comments.

[Copilot]

Pull request overview

Copilot reviewed 44 out of 44 changed files in this pull request and generated no new comments.

[nohwnd]

looks great

[Copilot]

Pull request overview

Copilot reviewed 46 out of 46 changed files in this pull request and generated 4 comments.