Refactor tests

[Zechiax]

Differentiate between unauthenticated/authenticated tests, allow running of unauthenticated tests on pull requests

[Copilot]

Pull Request Overview

This PR refactors the test structure to differentiate between authenticated and unauthenticated tests, enabling unauthenticated tests to run in pull requests while maintaining full test coverage in main branch builds.

Key changes:

• Split test base classes into UnauthenticatedTestBase and AuthenticatedTestBase
• Consolidated test data into a centralized TestData class
• Updated CI/CD configuration to run only unauthenticated tests on pull requests

Reviewed Changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
test/Modrinth.Net.Test/appsettings.json	Removed configuration file in favor of user secrets
test/Modrinth.Net.Test/ModrinthApiTests/EndpointTests.cs	Split into separate base classes for authenticated/unauthenticated tests
test/Modrinth.Net.Test/Modrinth.Net.Test.csproj	Added user secrets support and updated dependencies
.github/workflows/dotnet.yml	Updated CI to run different test sets based on context
README.md	Added testing documentation
Multiple test files	Updated to inherit from appropriate base classes and use centralized test data

Comments suppressed due to low confidence (1)

test/Modrinth.Net.Test/ModrinthApiTests/UserEndpointTests.cs:45

• [nitpick] The test method name suggests it should work with any valid ID, but the implementation uses the current user's ID from an authenticated context. Consider renaming to GetCurrentUserAsync_WithUnauthenticatedClient_ShouldReturnUser or similar to better reflect the test's purpose.

    public async Task GetUserAsync_WithValidId_ShouldReturnUser()