Spun out from T375235
Background
It is possible to have charts with a title and subtext
e.g. the text "Data from..." on https://echarts.apache.org/examples/en/editor.html?c=bar-polar-real-estate
Use story
TBC - what is the use case for adding subtext
Acceptance criteria
From T375235:
- Title subtext should be font size 14
- Title subtext color should be #54595D in light mode, #A2A9B1 in dark mode
