Add image picker form element

Problem/Motivation

Users should be able to pick images.

Proposed resolution

Add image picker form element

References

• https://rvera.github.io/image-picker/
• https://www.drupal.org/project/webform_imagepicker
• https://cdnjs.com/libraries/image-picker

Tasks

• Element type = webform_select_image
• Extends 'select'
• Add support for text/value option properties.
• Allow for advanced #options text,value,src.
• Serialize options data to select element and set attributes using JSON.
• Add limit message.
• Recommends IMCE to populate URL/Path.
• Support hide/show using wrapper
• Use remote placeholders for examples.

Properties

• #class=webform-select-image-value
• #image_show_label
• #image_limit (#multiple)
• #image_limit_message (#multiple_message)
• #image_hide_select: TRUE
• #images
• text
• value
• src
• alt
• label