add python.useEnvironmentsExtension (#25204)

step 1 of insiders envs ext rollout. In the activation function, set
`python.config.useEnvironmentsExtension:true` (so for everyone with envs
extension installed). Result: all users with extension envs extension
installed (and using it while we have this bake) will get this in their
user settings and thus when experimentation starts they will override
any control/treatment group.

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.",