Email Alert - inconsistent modals between dashboard vs Settings > Alert & Report flow

[zuzana-vej]

Thanks for recent launch of updated email & report setup modal

As per this discussion, the modal for Email and Alert was redesigned and released in Superset 4.0.
We have observed some non-ideal behavior between the two flows and wanted to raise the inconsistencies:

1. When user is using the flow from a dashboard - user can (correctly) setup new email report. When you then go to "manage email report" again, you can see check box that there are active emails. The check box is very unintuitive - whether that de-activates set scheduled or not. Toggle would be more intuitive - similar as on the page you get from Settings > Alerts & Reports.

2. The modal that pops up when accessing from dashboard is different (more limited in settings) to the modal that pops up from accessing from Settings > Alerts & Reports. Is that intended? For example users can't set other recipient. At minimum - if this is intentional - it would be good to let users know that more comprehensive settings can be accessed via Setting > Alerts & Reports.
   2b) Related to point (2) user can only schedule one report from the dashboard flow. While they can schedule multiple reports to single dashboard from the Settings > Alerts & Reports flow.

3. Bug - this I believe is bug - currently the email report only does first tab of the dashboard. if the first tab doesn't contain any charts - and only contains markdown with text, the entire email fails - user receives text "Error: Report Schedule execution failed when generating a screenshot." in email. This is pretty unintuitive for users.Is there reason for this? As much as screenshot of markdowns on first tab of dashboards may not be most useful, the email also has link to dashboard which is useful. It would be preferred that email still contains a screenshot and link rather than just this error.

cc @yousoph @eschutho