[Self-Hosted] Notify Self-Hosted Users when they lost features above 10 users

[lucasvaltl]

Is your feature request related to a problem? Please describe

Currently, errors due to licensing issues are not handled. This means that:

• If a feature is not available to a use a feature (in the dashboard), there is a silent error in the javascript console but no notification to the user. Specifically, the EE_License_Required Error (see [dashboard] Handle EE_LICENSE_REQUIRED #3918)

Describe the behaviour you'd like

• From a technical perspective: We should handle licensing errors that are currently silent and make them explicit to the user
• From a product perspective: We need to be able to gracefully communicate to the users of a self-hosted installation that they are losing features because they went over 10 users. This can be done via a notification, e.g. a toast. A regular developer should not have this in their face 100% of the time though - they should be able to disable this and continue developing on a reduced feature set. An admin should be able to always to see this information - and they already can via the newly introduce License tab.

Describe alternatives you've considered

• Do nothing - would result in a bad user experience.

Additional context

• Replaces [dashboard] Handle EE_LICENSE_REQUIRED #3918 which has the exact same intent but was an old ticket with outdated wording.
• Internal RFC around this topic

Requires: #8933

[mrsimonemms]

Initially I thought it might not be right to have this sent to every user, but I think I was wrong - admins may not be on Gitpod daily but users will be, so their the "front-line" who can notify the admins if necessary

[gtsiolis]

Similarly with #9974 (comment), a global alert component could be used for informing admins or even users about the license status.