Simplify MMS apn setup by suggesting entries from mobile-broadband-provider-info database

Similar to the APN selection in g-c-c for mobile data it would be good if parameters like mmsc/apn/proxy could be picked for MMS via suggestions from m-b-p-i as well. There's two solutions here

• move that to g-c-c as well (it would somewhat fit into the mobile panel)
• do that in chatty as we have the parameters in the MMS settings anyway

Currently this feature is implemented in mmsd itself so there's code to build on. The desire to move it out of mmsd itself came from https://gitlab.com/kop316/mmsd/-/issues/63 since we might need additional bearers. Note that chatty won't store the information but pass it on to mmsd (and maybe another component that sets up neaded bearers).

@tobias.bernard @sam.hewitt any opinions here?

/cc @kop316