Migrate vscode-extension-tester to 3.x

[xorye]

From README.md for https://github.com/redhat-developer/vscode-extension-tester:

Migrating to 3.x

The vscode-extension-tester package still integrates the same way as in older versions, with one slight difference.

If you wish to use the native dialog handlers, you will need to install an additional module vscode-extension-tester-native. The appropriate classes will then still be exported from the main module to keep code compatibility.

One aim of 3.x is to provide a more convenient way of updating to new VS Code releases. The modular approach allows us to publish updates to packages like page objects or locators without updating the main module. If such an update occurs, you should get it on the next npm install in your project without making changes to your package.json. Unless your package-lock.json decides otherwise.

The updating locators would be helpful for running the UI tests against the latest VS Code version. Currently, the UI tests are always running on version 1.42.1:

vscode-quarkus/package.json

Line 336 in 55f8a77

"test-ui-run": "extest setup-and-run 'out/test/vscodeUiTest/suite/*.js' -u -c 1.42.1",

Keeping it at 1.42.1 could be problematic because newer versions of vscode-java (an extension dependency for vscode-quarkus) currently requires a minimum version of 1.44.0. Therefore the current UI tests are testing vscode-quarkus alongside an older version of vscode-java, which might not be a common scenario moving forward.

Also, the current UI tests use the native dialog handlers when selecting a directory during the project generation tests, therefore we need vscode-extension-tester-native as described in the readme.