Fix: show/hide widgets features cannot handle complex input fields like Image or FileUpload

[alberndt]

Currently the show/hide-widgets features works only for simple dialog fields. More complex dialog fields of Coral UI using a wrapper DIV (e.g. Image, FileUpload), and the jQuery selector of show/hide-widgets will hide the field, but never unhides it.

This is because the css-class is assigned to the wrapper DIV, while the "showhidetargetvalue" is rendered at the main input field. I extended the jQuery selector to unhide also dialog-field, when they contain an input-element with showhidetargetvalue.

The following cq:dialog is an example, that works after the fix (and not before).

{
  "image": {
    "useHTML5": true,
    "mimeTypes": [
      "image"
    ],
    "name": "./file",
    "fieldLabel": "Image",
    "allowUpload": false,
    "sling:resourceType": "granite/ui/components/foundation/form/fileupload",
    "uploadUrl": "${suffix.path}"
  },
  "altText": {
    "name": "./altText",
    "fieldLabel": "ALT Text",
    "sling:resourceType": "granite/ui/components/foundation/form/textfield"
  },
  "enableSmallImage": {
    "cq-dialog-showhide-target": ".dch-small-image-widget",
    "name": "./enableSmallImage",
    "text": "Enable alternative Image for small screens",
    "sling:resourceType": "granite/ui/components/foundation/form/checkbox",
    "cq-dialog-checkbox-showhide": ""
  },
  "imageSmall": {
    "useHTML5": true,
    "showhidetargetvalue": true,
    "mimeTypes": [
      "image"
    ],
    "name": "./imageSmall/file",
    "class": "dch-small-image-widget",
    "fieldLabel": "Alternative Image (small screens)",
    "allowUpload": false,
    "sling:resourceType": "granite/ui/components/foundation/form/fileupload",
    "uploadUrl": "${suffix.path}"
  },
  "altTextSmall": {
    "showhidetargetvalue": true,
    "name": "./imageSmall/altText",
    "class": "dch-small-image-widget",
    "fieldLabel": "ALT Text (small screens)",
    "sling:resourceType": "granite/ui/components/foundation/form/textfield"
  }
}