Added PDFGenerator available check to download PDF button.
Added PDFGenerator available check to download PDF button.

- Added PDFGenerator available check to download PDF button before running show/hide or enable/disable commands on it. This was causing JS error running actions when button is not in toolbars.
- Refactored code that was running JS commands on toolbar buttons to show/hide or enable/disable them.
(transferred from ManageIQ/manageiq@633065132a7072df38716a8ab45dec6c123ffdc9)

ManageIQ/manageiq-ui-classic,ManageIQ/manageiq-ui-classic,ManageIQ/manageiq-ui-classic,ManageIQ/manageiq-ui-classic