Switch to using the installExtension command for offline/insider vsix installing #3408
Description
They added it to 1.33.0.
vscode.commands.executeCommand('workbench.extensions.installExtension', vscode.Uri.file('path-to-vsix'));
The problem with the current method is that it has to locate the .exe, which may fail for various reasons (such as the .exe name not matching what we expect).