Fix bugs in attribute outputs page

Fix bugs in attribute outputs page

  * Attributes being added to the template for each output
    declared if the attribute is a property and has a value
  * Unable to set a default value on a property from Output page
  * Fix issues with the save button
    * infinite save pop up when trying to leave the page with
      changes and clicking save
    * parse error in the console that would make the save button
      remain enabled after save was succesful
  * output values not being removed from attribute after output
    is deleted
  * nested attribute values not being updated

Issue-ID: SDC-4632
Signed-off-by: JvD_Ericsson <jeff.van.dam@est.tech>
Change-Id: I08abd6cd96963b09be7941c3a91559e241ace24f