Fixes#8433
* Adds E2E test to `test` script in gui2 (without server)
* Add options to `run` script to specify what test should be run: `unit` (default), `e2e`, or `ci` (which runs both unit and e2e without watching/spawning report server).
* The CI test step now checks e2e tests.
### Important Notes
~~One of e2e tests was disabled because it caught the regression on develop: #8476 ~~
- Closes#8179
# Important Notes
- ⚠️ These tests are currently *not run* on any CI workflow.
- There is some unused code for mocking the PM. This has been intentionally kept, as this may be useful in the future.
Note that this may be useful for testing the dashboard, however the dashboard is currently only tested in cloud mode
- that is, without the backend switcher, and with only the remote backend available. As such, currently it uses HTTP API mocks, and no PM mock.
# Important Notes
- Binary LS endpoint is not yet handled.
- The parsing of provided source is not entirely correct, as each line (including imports) is treated as node. The usage of actual enso AST for nodes is not yet implemented.
- Modifications to the graph state are not yet synchronized back to the language server.
