Fix comparison in TaskHostParameters

[YuliiaKovalova]

This change introduces a new read only struct that is used in Dictionary for caching in TaskRegistry
#12620

Without a proper equality check it spawns a new process due to mismatch.

Experimental insertion without extra allocation reported: https://devdiv.visualstudio.com/DevDiv/_git/VS/pullrequest/686770

[Copilot]

Pull Request Overview

This PR implements proper equality semantics for the TaskHostParameters struct by adding IEquatable<TaskHostParameters>, Equals, and GetHashCode implementations. The changes ensure that task host parameter comparisons correctly consider only the identity properties (Runtime, Architecture, and TaskHostFactoryExplicitlyRequested) and use case-insensitive string comparisons, while excluding path properties (DotnetHostPath and MSBuildAssemblyPath) from identity checks.

Key changes:

• Adds IEquatable<TaskHostParameters> implementation with case-insensitive string comparison for Runtime and Architecture
• Implements GetHashCode using a manual hash code calculation compatible with .NET Framework 4.7.2
• Updates ToDictionary() to use StringComparer.OrdinalIgnoreCase for consistency
• Refines IdentityParametersMatch in TaskRegistry.cs to explicitly exclude path properties from exact match comparisons

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/Framework/TaskHostParameters.cs	Implements IEquatable<TaskHostParameters>, adds Equals and GetHashCode methods, and updates ToDictionary to use case-insensitive string comparer
src/Build/Instance/TaskRegistry.cs	Removes path property comparisons from exact match logic in IdentityParametersMatch to align with the new equality implementation
.mcp.json	Adds MCP server configuration file (appears unrelated to the core PR purpose)

Comments suppressed due to low confidence (1)

src/Build/Instance/TaskRegistry.cs:914

• With the new GetHashCode implementation in TaskHostParameters, this code could be simplified to call obj.TaskIdentityParameters.GetHashCode() directly instead of manually computing hash codes for Runtime and Architecture. This would ensure consistency and reduce code duplication.

                        int runtimeHash = obj.TaskIdentityParameters.Runtime == null ? 0 : StringComparer.OrdinalIgnoreCase.GetHashCode(obj.TaskIdentityParameters.Runtime);
                        int architectureHash = obj.TaskIdentityParameters.Architecture == null ? 0 : StringComparer.OrdinalIgnoreCase.GetHashCode(obj.TaskIdentityParameters.Architecture);