[Alerts][License] Ability to phrase the licensing error message text with the CTA support.

[YulNaumenko]

Add a possibility to phrase the licensing error message text in which the CTA can live with the manage license button.
If user is the administrator, we should keep a streamlined navigation experience, in the other case we should manage this behavior differently.
Currently all users get the message like this:
'Alert test.gold.noop is disabled because it requires a Gold license. Contact your administrator to upgrade your license.',
Should keep the same UX for Alerts and Connectors.

[elasticmachine]

Pinging @elastic/kibana-alerting-services (Team:Alerting Services)

[mikecote]

The same should apply for connectors as well.

[mikecote]

Moving from 7.x - Candidates to 8.x - Candidates (Backlog) after the latest 7.x planning session.

[ryankeairns]

Just posted a similar comment on a PR, but here is a quick suggestion on the modal copy:

Since we can't very easily determine what role a person has - or what they have the ability to do - perhaps the text ought to be more general and we leave the available options up to the License Management page.

The modal title and text would be:

Gold license required

Alert test.gold.noop is disabled because it requires a Gold license. Continue to the License Management page to view upgrade options.

[ Cancel ] [ Manage license ]

[gchaps]

A minor tweak.

Gold license required

Alert example.people-in-space is disabled because it requires a Gold license. Continue to License Management to view upgrade options.

[ Cancel ] [ Manage license ]