Extended Page Schemas integration

1. Allow to specify field description and "before field" text in generated form
2. Allow to choose which standard inputs will be available in generated form (free text, minor edit, preview button, etc)
3. Adds some new hooks in field template generation:
 - 'SfTemplateFieldBefore', allow to specify "before" text for generated template
 - 'SfTemplateTextBefore', allow to specify "before" text for field in template
 - 'SfTemplateFieldAfter', allow to specify "after" text for field in template
 - 'SfTemplateFieldArrayMap', allow to specify template for list-type fields
 - 'SfTemplateTextAfter', allow to specify "after" text for generated template

Change-Id: I10276b51c5fc755efb6ffce6390de47aac10cdc7
Merge "Extended Page Schemas integration"