[FEATURE REQUEST] stop usage of the internal folder

[elee1766]

hi

we are using asynq for a while in some production services and love it!

reading through some prs here - see that you would prefer to keep development in this repository, and we totally agree that its the best option.

however - we are looking to build extensions/interfaces which require us to be able to access the protos in /internal. for instance, and alternative client, which is something we think shouldnt live in the package itself, but better published as a third party module which depends asynq.

this would also allow faster iteration on top of asynq which does not explicitly require your attention and

so i think it would be good to rename /internal -> /pkg

the alternative is that we will just continue to use a forked asynq and replace in all our projects in order to use our extensions.

if you agree, happy to make the pr.