Add rails db:migrate to Spring-enhanced commands

[f1sherman]

I noticed recently that running bin/rails db:migrate on our app is much slower than bin/rake db:migrate and tracked that down to db:migrate not being a Spring-enhanced command. Given that many Rails developers run this command quite often, possibly more often than some of the other Spring-enhanced commands, it seemed to make sense to add it.

I wasn't sure if I should add all of the db:migrate* tasks (e.g. db:migrate:redo). Since db:migrate probably gets run much more often that those others in many use cases this seems to satisfy the 80/20 rule. I'm happy to add those other commands if that's desired.

I didn't see any test coverage for similar commands, let me know if I should add anything.

Thank you!

[kaspth]

Nice! Since we'd also want this for db:rollback and db:migrate:redo, is it possible to teach Spring to look for bin/rails where it once looked for bin/rake (keeping the bin/rake lookup)? Because it must've had that, and that way we'd get it automatically for all the past enriched commands.

[f1sherman]

@kaspth great question! I'm sorry but I think I'd need a couple more hours diving in to the source to get a feel for how I might make that change, and I'm not able to commit to that at this time.