A simple Background Worker that uses SPI (connected to a local database named postgres) in a
transaction.
In order to use this bgworker with pgrx, you'll need to edit the proper postgresql.conf file in
~/.pgrx/data-PGVER/postgresql.conf and add this line to the end:
shared_preload_libraries = 'bgworker.so'
Background workers must be initialized in the extension's _PG_init() function, and can only
be started if loaded through the shared_preload_libraries configuration setting.