Add comprehensive tests for resolveAndUpdatePythonPath prioritization logic (microsoft#842)

* Initial plan

* Add comprehensive tests for resolveAndUpdatePythonPath prioritization logic

Co-authored-by: eleanorjboyd <26030610+eleanorjboyd@users.noreply.github.com>

* add tests for resolveAndUpdatePythonPath

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: eleanorjboyd <26030610+eleanorjboyd@users.noreply.github.com>

Author: Copilot

.vscode/launch.json

@@ -27,9 +27,9 @@
                 "--extensionDevelopmentPath=${workspaceFolder}",
                 "--extensionTestsPath=${workspaceFolder}/out/test/unittest/index"
             ],
-            "env": {
-                "TEST_GREP": "Python API Tests"
-            },
+            // "env": {
+            //     "TEST_GREP": "Python API Tests"
+            // },
             "outFiles": ["${workspaceFolder}/out/**/*.js"],
             "preLaunchTask": "tasks: watch-tests"
         }