Get vega chart tooltip and cursor available by default

[thomasdanan]

Component:

'chart'

Why this is needed:

cursor and tooltip greatly help to read a chart. It has been introduced in some applications leveraging the core-ui vega chart component. In order to have a unified experience when working with charts, it would make sense to have the tooltip always actvated. It can be deactivated in some specific cases by the application.

What should be done:

Activate chart cursor and tooltip by default.
Permit an application to deactivate it.

Implementation proposal (strongly recommended):

Test plan: