Improve error for static attribute attempts

[composerinteralia]

Some people upgrade straight from factory_bot < 4.11 to factory_bot >=
5.0 and miss the deprecation cycle for static attributes. I have gotten
some feedback that the NoMethodError is confusing. Since we know that in
most cases people are seeing the NoMethodError when trying to define
static attributes, we offer them a "Did you mean?"-style suggestion for
how they might update to dynamic attributes.

I removed the extra test for setter methods. It was a remnant of
something I had removed in #1200. I see no reason to have special
treatment for setters at this point.

Closes #1272

[seanpdoyle]

I see that args.first is used a few times in this method. Would it be worth extracting a variable to help describe why args.first is significant?

What do you think about:

def method_missing(name, *args, &block)
  attribute_value = Array(args).first  # coercing with `Array()` might not be necessary with splats

  if attribute_value.nil?
    # ...
  elsif attribute_value.respond_to?(:has_key?) && attribute_value.has_key?(:factory)
    # ...
  else
    # ...
  end
end

[composerinteralia]

I like it. I adjusted the name a little and pulled out a private predicate method. What do you think:

def method_missing(name, *args, &block)
  association_options = args.first # AFAIK args will always be an array

  if association_options.nil?
    # ...
  elsif __valid_association_options?__(association_options)
    # ...
  else
    # ...
  end
end

private

def __valid_association_options?(options)
  options.respond_to?(:has_key?) && options.has_key?(:factory)
end