[Feat Request] Introduce session check when running spec

[pozil]

Is your feature request related to a problem? Please describe

When running tests, there's a good change that we either forget to log in or that a session that we obtained earlier has expired.
If this is the case, we are blocked on the login page and the tool performs a series of retries that will lead to an unclear error after timing out.

Describe the solution you'd like

I'm suggesting a solution that I've implemented in the E-Bikes sample app.

Let's save a timestamp when we generate the env file with the login URL:
https://github.com/trailheadapps/ebikes-lwc/blob/main/scripts/generate-login-url.js#L36

In our spec, we then read the timestamp and figure out if if the session has expired:
https://github.com/trailheadapps/ebikes-lwc/blob/main/force-app/test/utam/page-explorer.spec.js#L27

If this is the case, we abort the test with a clear error message.
https://github.com/trailheadapps/ebikes-lwc/blob/main/force-app/test/utam/page-explorer.spec.js#L31

[olivier-martin-sf]

Hi @pozil, that's indeed an improvement and a great suggestion, do you feel like implementing a PR for this? Thank you for such a helpful contribution