Add SBOM, symbols, traces, and VEX files for CVE-2022-21661 SQLi case

- Created CycloneDX and SPDX SBOM files for both reachable and unreachable images.
- Added symbols.json detailing function entry and sink points in the WordPress code.
- Included runtime traces for function calls in both reachable and unreachable scenarios.
- Developed OpenVEX files indicating vulnerability status and justification for both cases.
- Updated README for evaluator harness to guide integration with scanner output.

src/Signals/StellaOps.Signals/Properties/AssemblyInfo.cs

@@ -0,0 +1,4 @@
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("StellaOps.Signals.Reachability.Tests")]
+[assembly: InternalsVisibleTo("StellaOps.ScannerSignals.IntegrationTests")]