[FEATURE REQUEST] Add Font size field

[darigovresearch]

Is your feature request related to a problem? Please describe. Allow for defining the size for the font for numbers

Describe the solution you'd like Could be a number field

Describe alternatives you've considered Could also be a slider

Additional context Based on suggestion from @ronaldbradford in https://github.com/Robbbb/VectorRuler/pull/38#issuecomment-1646877681