Add gem configuration, with base component customization

[joelzwarrington]

• Closes It'd be nice to have the ability to customize the base class so that it can inherit our own class #159

What

• Adds a configuration object singleton to ViewComponent::Form
• Adds configuration option parent_component which all ViewComponent::Form components inherit from, and defaults to ViewComponent::Base

Why

So that one can define shared logic without having to use concerns or building their own components that don't inherit from their ViewComponent::Form component counterpart.

As an example, let's say I'd like to use the heroicon gem to add icons to my fields, I can do that easily by defining my own ApplicationFormComponent

class ApplicationFormComponent < ViewComponent::Base
  include Heroicon::Engine.helpers
end

or, if I'm using Tailwind, I could use tailwind_merge to merge HTML classes to avoid conflicts, etc.

[Spone]

Thanks for taking a stab at this!

[Spone]

Do we need this line? Can Zeitwerk autoload the constant without it?

[joelzwarrington]

I ran the test suite without it in d1e420c and it seems to be loaded just fine!

I'll do another test in my production Rails application.

[Spone]

@joelzwarrington mind adding a note to the CHANGELOG?

[joelzwarrington]

Yep, I'll add a note to the change log 😄