add global field settings

Allow users to set global field settings. These would be set via the settings and uiSettings of the root field and would initially affect settings such as "display as modal". When new fields are added, the initial value of these properties will match the one defined for the root field (so in fieldTypes.jsx we will set it based on the global value from the state). This will be beneficial for users as they won't need to repeatedly change certain settings for each single field they add.