feat: completion list suggests methods in the order we most likely want

[mustakimali]

When typing MyType:: the completion items' order could be re-ordered based on how likely we want to select those:

• Constructors: new like functions to be able to create the type,
• Builder Methods: any builder methods available,
• Constructors that take args: Any other function that creates Self,
• Regular methods & associated functions (no change there)

In this photo, the order is:

• new constructor is first
• new_builder second is a builder method
• aaaanew is a constructor that takes arguments, is third and is irrespective of its alphabetical order among names.

I've dropped my previous idea of highlighting these functions in the rustdoc (rust-lang/rust#107926)

[rustbot]

There are merge commits (commits with multiple parents) in your changes. We have a no merge policy so these commits will need to be removed for this pull request to be merged.

You can start a rebase with the following commands:

$ # rebase
$ git rebase -i master
$ # delete any merge commits in the editor that appears
$ git push --force-with-lease

The following commits are merge commits:

• 14dbf18
• 6091d22

[rustbot]

There are merge commits (commits with multiple parents) in your changes. We have a no merge policy so these commits will need to be removed for this pull request to be merged.

You can start a rebase with the following commands:

$ # rebase
$ git rebase -i master
$ # delete any merge commits in the editor that appears
$ git push --force-with-lease

The following commits are merge commits (since this message was last posted):

• 27e3cff