add get-deps provider

[talentdeficit]

a no-op provider that depends on lock that is slightly more discoverable and user friendly

[tsloughter]

[talentdeficit]

someone on slack had a valid use case!

and it was @ferd!

[ferd]

Yeah one was fetching deps just before putting them in a docker image without having compiled them. At least get-deps does not carry the feeling of "I want to install a dep in a directory" or something.

[tsloughter]

Fine :). And I guess the name should stay as get-deps since it is what people from rebar2 would expect.

[ferd]

yeah. I was toying with the idea of rebar3 prepare but I guess it would be very ambiguous in terms of what it should do. I don't have any strong opposition to get-deps either. Do we want the docline for the command to refer to the lockfile or we mostly ignore it?

[alinpopa]

Sorry guys, I sort of needed that, but @ferd pointed me to rebar3 lock which works fine for me. Thanks. But I do agree that get-deps is "slightly more discoverable and user friendly".