feat: add options to customize the number of grid lines in select ROIs

[stropitek]

This will be helpful to guide rotation of ROI to make them straight

[cloudflare-workers-and-pages]

Deploying react-roi with    Cloudflare Pages

Latest commit:	a26f234
Status:	✅  Deploy successful!
Preview URL:	https://2a703ecc.react-roi.pages.dev
Branch Preview URL:	https://variable-grid-size.react-roi.pages.dev

View logs

[tpoisseau]

SGTM
It would be great to have props to style grid lines (line width, transparency, color, patterns like dots or dash). It can be done in another PR.

[stropitek]

It would be great to have props to style grid lines (line width, transparency, color, patterns like dots or dash). It can be done in another PR.

It already exists to some extent. But it is implemented in a callback, therefore there are no controls in the stories to set them. There is an option to set the color of the size controls in the corners, and grid lines take the same color, and a separate option to set grid lines opacity specifically.