Update AASM compiler to handle custom name and namespace

[jeffcarbs]

Motivation

When trying to replace our home-rolled DSL compiler for AASM, we realized the tapioca one does not handle two features of AASM we're relying on:

• using a custom name (i.e. aasm(:status) { }).
• using a namespace (i.e. aasm(namespace: :foo) { }).

This PR adds tests for those and updates the compiler to support them.

Implementation

When you call SomeClass.aasm you're actually implicitly calling SomeClass.aasm(:default) which tells AASM to create a state machine with the name :default. This means that if you define your state machine like aasm(:something), it's saved under the name :something so when you call aasm (again, which is really aasm(:default)) you're going to see an "empty" state machine with no states or events because you're looking at a totally different state machine.

Here's the source: https://github.com/aasm/aasm/blob/2e952ff2088082c9f00c95e3c1261afc826f737c/lib/aasm/aasm.rb#L27-L64

This PR updates the compiler to look at all state machines for a given constant when gathering the states and events for which to generate RBI.

If you're using a namespace:

• for states, the namespace is added to some_state? and STATE_SOME_STATE (source)
• for events, methods are created with and without the namespace (source)

Tests

I added failing specs, then in the second commit wrote the code to make them pass.

[paracycle]

Added a default state machine here as well, to test a class having multiple state machines.

[paracycle]

Thanks!