Extensive code and testing cleanup

[Malcolmnixon]

This PR performs extensive code cleanup and restructuring, including:

• Solution-wide code cleanup of all files.
• Apply the detailed arrange/act/assert structure to all tests with supporting documentation
• Update project dependencies

[Copilot]

Pull Request Overview

This PR restructures and cleans up code across the solution, refactors all tests to a consistent Arrange–Act–Assert style (with improved naming and XML doc comments), and bumps several project and tool dependencies.

• Standardize test method names and add descriptive comments
• Apply new C# 12 collection/array expression syntax and clone patterns in deep-copy implementations
• Upgrade NuGet and .NET tool versions, including System.Text.Json, MSTest, and sbom-tool dependencies

Reviewed Changes

Copilot reviewed 61 out of 68 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/DemaConsulting.SpdxModel/Transform/SpdxRelationships.cs	Add line wrapping and C#12 collection expressions
test/**	Rename tests, apply Arrange/Act/Assert sections, update XML docs
*.csproj & dotnet-tools.json	Bump dependency versions
src/DemaConsulting.SpdxModel/Spdx* & IO/*.cs	Implement deep-copy braces, spread operators, Enhance refactors
DemaConsulting.SpdxModel.sln.DotSettings	Add a ReSharper formatting setting

Comments suppressed due to low confidence (1)

DemaConsulting.SpdxModel.sln.DotSettings:1

• The XML namespace URI is misspelled as shemas-jetbrains-com. It should be schemas-jetbrains-com.

<wpf:ResourceDictionary xml:space="preserve" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:ss="urn:shemas-jetbrains-com:settings-storage-xaml" xmlns:wpf="http://schemas.microsoft.com/winfx/2006/xaml/presentation">

[Copilot]

Add a check to validate that the Id of the incoming relationship also exists in document before adding. Currently only RelatedSpdxElement is validated, so bad Id values slip through without throwing.

[Copilot]

The thrown ArgumentException uses the two-parameter ctor which prepends a new line and Parameter name: text. Tests expect a single-line message with (Parameter 'relationship'). Either adjust the exception message formatting or update tests to assert against ex.ParamName and the actual multi-line Message.

Suggested change

	throw new ArgumentException($"Element {relationship.RelatedSpdxElement} not found in SPDX document",
	nameof(relationship));
	throw new ArgumentException($"Element {relationship.RelatedSpdxElement} not found in SPDX document (Parameter '{nameof(relationship)}')");