Adding helper method for defaults.

[jwoertink]

Fixes #547

When we merged in #411 this broke the ability to easily set defaults on your query objects.

Before that PR you could do this:

class SomeQuery < User::BaseQuery
  def initialize
    age.gte(21)
  end
end

# WHERE age >= 21
SomeQuery.new

After that PR, you would have to manually set the query object to get the same effect

class SomeQuery < User::BaseQuery
  def initialize
    self.query = age.gte(21).query
  end
end

With this PR, you can still set the query object manually if you want, but this adds in a new defaults method to make it a little more clear on what your intension is. Note that this method is set to private because you shouldn't call this from outside of the query class.

class SomeQuery < User::BaseQuery
  def initialize
    defaults &.age.gte(21)
  end
end

# WHERE age >= 21
SomeQuery.new

[matthewmcgarvey]

🎉