Prioritize local types when auto-completing in a `-spec`

[robertoaloi]

Describe the bug

When completing in a -spec context, we can potentially return a huge list of atoms.
Local types are lost in that list.

To Reproduce**

Define a local type:

-type my_integer() :: integer().

Then start composing a -spec attribute:

-spec foo(my_in~

Expected behavior

The my_integer/0 type appears at the top of the list of completions.

Actual behavior

The type is there, but lost in the sea of all available atoms.