Get Repository Name

[aj-foster]

This PR is related to hexpm/hex#931.

In order to enable the modification of hex repositories without the need for a --name flag, this change adds hex_registry:get_repository_name/2.

After further discussion, this PR makes a breaking change to the return type of several registry-reading functions to return additional information that may be useful in the future.

[wojtekmach]

Thank you for the PR! Let's hold off on it for a moment given this comment https://github.com/hexpm/hex/pull/931/files#r803454950

[aj-foster]

@wojtekmach Not sure if you wanted to go ahead and include repository as a top-level key; just pushed a commit that does so. Easy to change if you'd prefer to keep only packages for now.

[wojtekmach]

@aj-foster perfect, thank you! Could you do the same thing for functions for other registry files, that is decode_versions and decode_package?

[aj-foster]

Sure thing. I went ahead and had each decoder return all of the top-level keys from each file (repository from versions; repository and name from packages).

[wojtekmach]

hmm, actually should we just go with this?

Suggested change

	#{repository := Repository, packages := Packages} = hex_pb_names:decode_msg(Payload, 'Names'),
	{ok, #{repository => Repository, packages => Packages}};
	{ok, hex_pb_names:decode_msg(Payload, 'Names')}.

as long as it's safe, i.e. decode_msg doesn't return an error tuple or something?

in hindsight, it was a big mistake to initially return just the subset of the protobuf, just the packages field. With this change we're in sync with the protobuf which means if we ever add another field, we'll immediately start returning it here.

[aj-foster]

Went ahead and made this change in 85e5964 — easy to revert if necessary. I also made the similar change to decode_versions/2 and decode_package/3.

Edit: there was a choice to make for the "verified" function clause, which could use review. I have it verifying the same fields for now.

[wojtekmach]

Thank you! Seems there are some transient issues on CI so I'll merge this afterwards.

[wojtekmach]

Thank you!