Add core package to testables for Unity tests

Include com.ivanmurzak.unity.mcp in the "testables" arrays so test assemblies can access the core package. Updated Unity-Package/Packages/manifest.json and Unity-Tests manifests for 2022.3.62f3, 2023.2.22f1, and 6000.3.1f1 to add the package alongside the existing particlesystem testable.

Author: IvanMurzak

Unity-Package/Packages/manifest.json

@@ -31,5 +31,6 @@
         "org.nuget.r3"
       ]
     }
-  ]
+  ],
+  "testables": ["com.ivanmurzak.unity.mcp"]
 }

Unity-Tests/2022.3.62f3/Packages/manifest.json

@@ -45,5 +45,5 @@
       ]
     }
   ],
-  "testables": ["com.ivanmurzak.unity.mcp.particlesystem"]
+  "testables": ["com.ivanmurzak.unity.mcp.particlesystem", "com.ivanmurzak.unity.mcp"]
 }

Unity-Tests/2023.2.22f1/Packages/manifest.json

@@ -48,5 +48,5 @@
       ]
     }
   ],
-  "testables": ["com.ivanmurzak.unity.mcp.particlesystem"]
+  "testables": ["com.ivanmurzak.unity.mcp.particlesystem", "com.ivanmurzak.unity.mcp"]
 }

Unity-Tests/6000.3.1f1/Packages/manifest.json

@@ -49,5 +49,5 @@
       ]
     }
   ],
-  "testables": ["com.ivanmurzak.unity.mcp.particlesystem"]
+  "testables": ["com.ivanmurzak.unity.mcp.particlesystem", "com.ivanmurzak.unity.mcp"]
 }