Add maker command for form type extensions

[yceruto]

I've two versions of this command:

1. This asks only for the class name of the form type extension and the extended type is always the FormType::class. Then, the user is responsible for changing it if necessary (with IDE autocompletion this task is very fast).
2. (The current one) Ask also for the FQCN of the extended type + class exists validation, but it could be a boring task considering that most of the time this form type comes from a vendor with a long namespace. To improve it, I thought about injecting all available form types and allowing the input of the class name only, something similar to what was done with the command debug:form <FormType> argument.

closes #78

[yceruto]

Anyone there!? :) very low review activity on this amazing new bundle by the way 🚤 I'd like to put 2th gear

[javiereguiluz]

It looks OK to me. Thanks Yonel.

[yceruto]

@javiereguiluz thanks for the minor reword ;) it looks better now.

[weaverryan]

Hey @yceruto!

Sorry for the delay - I wanted to get the new functional test system in place before working on any additional makers.

Imo, I would prefer option (2): where we allow the user to type in the extended type, but help them a bit (because yea, nobody wants to type the long class name, especially since \ needs to be doubled to \\ - I'm not sure if that's true anymore...). We do something similar in MakeSubscriber: we list all the events, then allow them to free-type, but with auto-completion. I agree that we should only make the user type the short version of the class name (e.g. FormType) (if there is a conflict, I guess we'll need to somehow use a less-shortened version... but that's an edge case).

Could you update the maker for these changes? Also, the FunctionalTest class has changed and there has been a slight change in MakerInterface after #97.

very low review activity on this amazing new bundle by the way 🚤 I'd like to put 2th gear

I agree :D. I think it's because I've been busy with some "boring" low-level tasks, but those are done now!

[yceruto]

Hi! happy new year to everyone 🎉

@weaverryan yeah, i'll try to do it this weekend, cheers.

[yceruto]

Latest changes:

• Added extended type argument.
• Show autocomplete values, populated with all "available" form types (core types + registered as services).
• Show ambiguous validation & choice question if there is more than one FQCN with the same CN.
• Added class exists validation to Validator.

Ready for review!

[yceruto]

Updated description with preview!

[yceruto]

this is ready from my side... ;)

[yceruto]

I'm closing here because I can't fix this after rebase on master.

[weaverryan]

@yceruto sorry about that - I should have communicated better. I wanted to get a few internal updates done (which are now done) before merging this. If you can’t rebate, I understand. But both of your PR’s are good imo :)