fix: DependsOnConflictAnalyzer reports all dependency cycles (#4862)

[thomhurst]

Summary

• Replace the Chain-based dependency traversal in DependsOnConflictAnalyzer with a proper DFS using a visited set and backtracking path list
• The old GetDependencies method returned immediately upon finding any already-traversed method, which prevented exploring other branches of the dependency graph and caused methods involved in cycles to go unreported
• Now all test methods that participate in dependency cycles correctly receive a TUnit0033 diagnostic, including those previously missed in class-level [DependsOn] scenarios with multiple test methods

Closes #4862

Test plan

• All 11 existing DependsOnConflictAnalyzerTests pass (verified on net9.0)
• Updated Direct_Conflict_Other_Class_Raises_Error and Direct_Conflict_Other_Class_Raises_Error_GenericAttribute tests to expect diagnostics on all 4 test method locations (previously only 2 of 4 were reported)
• Existing tests for no-conflict scenarios, base class scenarios, nested cycles, deep nested direct/indirect conflicts all continue to pass unchanged

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

The DFS-based cycle detection is a clean and correct replacement for the previous Chain-based traversal. A few things worth acknowledging:

• Algorithm correctness: The shared visited set (not backtracked alongside path) is intentional and sound. Since the dependency graph is static, if a node has no path back to targetMethod via one branch, it won't have one via another branch either — standard DFS reachability.
• Path reconstruction: The new[] { method }.Concat(cyclePath).Concat(new[] { method }) pattern correctly builds the full cycle description including both endpoints.
• continue instead of return: Switching early exits from return chain to continue is the key fix that allows the DFS to explore all dependency branches rather than short-circuiting on the first unresolvable attribute — this directly addresses the root cause of bug: DependsOnConflictAnalyzer only reports first dependency cycle #4862.
• Test updates: The test changes appropriately expand expected diagnostics from 2 to 4 for the cross-class dependency cycle scenarios, matching the corrected behavior.