[Lens] Show notification when data for y column or 'size by' is not-numerical

[mbondyra]

For last value metric operation, we only allow numerical values for xy charts and pie charts. However, numerical values can come as numbers or array of numbers. Array of numbers cannot be properly parsed by visualization which results in bad user experience:

The goal of this task is to display a notification that would allow a user to understand why their chart doesn't look as expected.

This is a followup task after #83437

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[mbondyra]

Implemented along with #83437 in a simple form.