Sync functionality to work "offline" (No API connection)

[itssimple]

• Ability to sync course templates (and other info needed to work "offline") Ability to sync course templates (and other info needed to work "offline") #148
• Ability to store bookings / inquiries in plugin, in case of API being down Ability to store bookings / inquiries in plugin, in case of API being down #149
• Custom page type with custom meta data (ability to build your own template if you want to create real pages) Custom page type with custom meta data #150
• WP-Cron to sync items in the background WP-Cron to sync items in the background #151
• Page Editor tools (For custom type page) Gutenberg - Shortcode preview with dummy data #152