Make more field validation messages scope aware

Feedback messages of validations specified on fields (required, email, etc) are now reported below the field. Some more field level validation can be shown there.

• validation on the format of a date field (add an invalid value, click Save)
• validation of uploaded assets and images (e.g. when only certain field types are allowed, or if the maximum file size is exceeded)

Notice that the upload components are used in documents, but also in dialogs in the images / assets sections.