Allow unqualified component syntax

Currently, package components need to be qualified by `PKG:test:TEST_NAME` / etc. However, when I was poking around the `Cabal` code I noticed that having components with different types but the same name is no longer supported. Since it will be unambiguous, we should allow `PKG:TEST_NAME`. One question is if you write `PKG:test`, to refer to a component called `test` should that be allowed? I think so.

I actually think it should have been this way even if Cabal did not enforce this constraint. If it is aliased, just build both.

Similarly, I would like to support `:component-name` syntax. This would build all the components in the local packages matching that name. We could even consider glob patterns, but that is getting a little wild maybe.