[ML] Use EUI Toasts for error and info messages

[elasticmachine]

Some of the pages in the ML plugin, such as the jobs list and creation pages, have their own message bar for displaying error and information messages - public/components/messagebar/messagebar_service.js. This should be replaced with EUI's toast notification system.

However in order to use the EUI Toasts, they need to allow for the expansion of server error messages in the UI (if a response is supplied), for example:

Currently there is no way to handle 'show more' information in a toast, and the EUI toast needs to be able to handle large stack trace information, which would currently overflow in the limited width that the toast currently allows.

One consideration is the use of error messages when displaying form mistakes for new jobs.
For example, if the user forgets to enter a job name, we currently display a error in the message bar and a local context specific message. Error messages should be automatically cleared once the user corrects the mistake and attempts another save.

Note the old Notifier system is currently used in:

• x-pack/plugins/ml/public/components/full_time_range_selector/full_time_range_selector_service.js

[elasticmachine]

Original comment by @sophiec20:

Relates LINK REDACTED

[peteharverson]

See related meta issue #31943

[jgowdyelastic]

also related #20880

[timroes]

This has now all been done via #41191 lately.