Add option filter on in_order_of

[igordepolli]

Motivation / Background

This Pull Request has been created because currently, in_order_of method always use where clause to filter the results only with the values specified in values. Sometimes, we only want to put some values as priority in the sorting but we want the entire search scope without caring about the rest of the sorting. The propose here is add an option to specify to filter scope by values or not.

Detail

This Pull Request changes:

order = [3, 4, 1]

# Without specify option
Post.in_order_of(:id, order).to_sql
# SELECT 
  # "posts".* FROM "posts" 
# WHERE 
  # "posts"."id" IN (3, 4, 1) 
# ORDER BY 
  # CASE WHEN "posts"."id" = 3 THEN 1 WHEN "posts"."id" = 4 THEN 2 WHEN "posts"."id" = 1 THEN 3 END ASC

# With option seted to false
Post.in_order_of(:id, order, filter: false)
# SELECT 
  # "posts".* FROM "posts" 
# ORDER BY 
  # CASE WHEN "posts"."id" = 3 THEN 1 WHEN "posts"."id" = 4 THEN 2 WHEN "posts"."id" = 1 THEN 3 ELSE 4 END ASC

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one change. Unrelated changes should be opened in separate PRs.
• Commit message has a detailed description of what changed and why. If this PR fixes a related issue include it in the commit message. Ex: [Fix #issue-number]
• Tests are added or updated if you fix a bug or add a feature.
• CHANGELOG files are updated for the changed libraries if there is a behavior change or additional feature. Minor bug fixes and documentation changes should not be included.

[timoschilling]

I really like this idea, I had already the same, but you are faster ;)

Maybe only_values isn't the best name for the option. Some more ideas are:

• find which will be true by default and can be overwritten
• filter which will be true by default and can be overwritten

[igordepolli]

@timoschilling, ty very much for your review! I liked your idea, filter really is a better name and have taken your suggestion!

@admsev , thanks for the bot suggestions as well! I made the grammar correction and the other consistency correction it suggested!