pbx_config: Register manager actions with module version of macro.

Switch manager actions in pbx_config to use the registration macro that
passes the module pointer, allowing pbx_config reference to be bumped
while the manager actions run.

ASTERISK-25061 #close
Reported by: Corey Farrell

Change-Id: I422c50dd74814616ac10c5e9c6598a0b1bc2c44e