add exp setting for envs ext

Author: eleanorjboyd

package.json

@@ -440,6 +440,16 @@
                     "scope": "resource",
                     "type": "string"
                 },
+                "python.useEnvironmentsExtension": {
+                    "default": false,
+                    "description": "%python.useEnvironmentsExtension.description%",
+                    "scope": "machine-overridable",
+                    "type": "boolean",
+                    "tags": [
+                        "onExP",
+                        "preview"
+                    ]
+                },
                 "python.experiments.enabled": {
                     "default": true,
                     "description": "%python.experiments.enabled.description%",

package.nls.json

@@ -38,6 +38,7 @@
     "python.debugger.deprecatedMessage": "This configuration will be deprecated soon. Please replace `python` with `debugpy` to use the new Python Debugger extension.",
     "python.defaultInterpreterPath.description": "Path to default Python to use when extension loads up for the first time, no longer used once an interpreter is selected for the workspace. See [here](https://aka.ms/AAfekmf) to understand when this is used",
     "python.envFile.description": "Absolute path to a file containing environment variable definitions.",
+    "python.useEnvironmentsExtension.description": "Enables the Python Environments extension.",
     "python.experiments.enabled.description": "Enables A/B tests experiments in the Python extension. If enabled, you may get included in proposed enhancements and/or features.",
     "python.experiments.optInto.description": "List of experiments to opt into. If empty, user is assigned the default experiment groups. See [here](https://github.com/microsoft/vscode-python/wiki/AB-Experiments) for more details.",
     "python.experiments.optOutFrom.description": "List of experiments to opt out of. If empty, user is assigned the default experiment groups. See [here](https://github.com/microsoft/vscode-python/wiki/AB-Experiments) for more details.",

src/client/envExt/api.internal.ts

@@ -14,6 +14,7 @@ import {
 } from './types';
 import { executeCommand } from '../common/vscodeApis/commandApis';
 import { IInterpreterPathService } from '../common/types';
+import { getConfiguration } from '../common/vscodeApis/workspaceApis';
 
 export const ENVS_EXTENSION_ID = 'ms-python.vscode-python-envs';
 
@@ -22,7 +23,9 @@ export function useEnvExtension(): boolean {
     if (_useExt !== undefined) {
         return _useExt;
     }
-    _useExt = !!getExtension(ENVS_EXTENSION_ID);
+    const inExpSetting = getConfiguration('python').get<boolean>('useEnvironmentsExtension', false);
+    // If extension is installed and in experiment, then use it.
+    _useExt = !!getExtension(ENVS_EXTENSION_ID) && inExpSetting;
     return _useExt;
 }