dispatcher-modem-setup: new modem setup dispatcher

There are cases where the user wants to configure some actions
to be run on a modem before ModemManager takes over full control.

The new "modem setup" dispatcher scripts allow running operations
in the modem after the port probing has happened and we know which
ports are usable in the device.

The scripts may e.g. change device configuration, enable modem
logging infrastructure, or any other process that would otherwise
conflict with MM's own modem management operations.

src/meson.build

@@ -269,6 +269,7 @@ sources = files(
   'mm-dispatcher.c',
   'mm-dispatcher-connection.c',
   'mm-dispatcher-fcc-unlock.c',
+  'mm-dispatcher-modem-setup.c',
   'mm-filter.c',
   'mm-iface-modem-3gpp.c',
   'mm-iface-modem-3gpp-profile-manager.c',
@@ -308,6 +309,8 @@ endif
 c_args = [
   '-DMM_COMPILATION',
   '-DPLUGINDIR="@0@"'.format(mm_prefix / mm_pkglibdir),
+  '-DMODEMSETUPDIRPACKAGE="@0@"'.format(mm_prefix / mm_pkglibdir / 'modem-setup.d'),
+  '-DMODEMSETUPDIRUSER="@0@"'.format(mm_prefix / mm_pkgsysconfdir / 'modem-setup.d'),
   '-DFCCUNLOCKDIRPACKAGE="@0@"'.format(mm_prefix / mm_pkglibdir / 'fcc-unlock.d'),
   '-DFCCUNLOCKDIRUSER="@0@"'.format(mm_prefix / mm_pkgsysconfdir / 'fcc-unlock.d'),
   '-DCONNECTIONDIRPACKAGE="@0@"'.format(mm_prefix / mm_pkglibdir / 'connection.d'),