Set labels on charts and other widgets via msg

### Description

In Dashboard 1, it was possible to set a widgets label using mustache format. e.g. `{{topic}} temperature`

This is especially useful (for example) when pulling data from a database to display in a chart - you might want the title to read "Data for {{lineName}} for {{monthName}}"

I am not syaing we _must_ add mustache support but rather perhaps the label could support JSONata to permit it to be computed? Or could be updated via a specially crafter message.

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate