data-control: separate out a data_offer struct
This is a prerequisite to adding primary selection support.
data-control: separate out data_control_source
This is a prerequisite to adding primary selection support, since that
doesn't use wlr_data_source, but rather wlr_primary_selection_source.
Update the data-control protocol
data-control: add primary selection support
Merge create_offer and create_primary_offer
Extract code into data_control_source_destroy()
Fix pointer style
Move resource neutralization to destructor
Store wl_resource in the data_offer
Extract data_offer destruction into a function
9e49ceb129