The ExtensionMode is provided on the ExtensionContext and indicates the
mode the specific extension is running in.
Static variables
staticread onlyDevelopment:ExtensionMode
The extension is running from an --extensionDevelopmentPath provided
when launching the editor.
staticread onlyProduction:ExtensionMode
The extension is installed normally (for example, from the marketplace or VSIX) in the editor.
staticread onlyTest:ExtensionMode
The extension is running from an --extensionTestsPath and
the extension host is running unit tests.