Better handing for --demo

[mccalluc]

• Fix Handle --demo nicely on first tab #81: We can't actually set the value of the upload widget, but we can set placeholder text.
• Fix More explanation in UI when running with --demo #75: Add tool tips on the first tab if we're running with --demo

Does not address:

• After release, controls on previous pages should be locked #32

Eventually, we want the inputs on this screen to be frozen if they have been set from the CLI.

[ekraffmiller]

Looks good! UI Suggestion: When running with --demo, don't show the FileUpload component, since demo.csv is being used. Include some text about demo being used instead.

[ekraffmiller]

Approved with a follow up suggestion for UI

[mccalluc]

• Filed When running --demo, don't show the FileUpload component #113

[mccalluc]

App test fails:

        # -- Download results --
        page.get_by_role("button", name="Download results").click()
        expect_not_visible(pick_dataset_text)
>       expect_not_visible(perform_analysis_text)

Looking at the trace, it looks like it might have gotten bogged down in recalculating the graphs and didn't respond to the mouseclick to move to the next page quickly enough. Is there a risk of the application being unresponsive?

For now, just try to run run the tests.

[mccalluc]

• Filed Fix race conditions / timeouts in app test #116