This patch adds a segments option to solidify in simple mode. This feature was highly requested on rightclickselect at https://blender.community/c/rightclickselect/3wgbbc/#5ff1efb29c12217ab9e14d92
Adding the same option to complex solidify is much harder and is likely to cause slowdowns and other trouble.
The segments option is added below the offset slider for now. In the future I am likely going to revisit the UI of the solidify modifier, as some options are quite hidden currently.