Improvements to code complete for parameters

Currently if I use code complete when filling in the parameters to a function, the parameters are displayed in alphabetical order. It would be helpful if something like this were implemented:

- parameters are added by keyword. Ie clicking a a parameter "bar" in code complete added `bar=` to the function call.

- positional arguments appear in positional order in the code complete dropdown

Furthermore it would be helpful if code complete displayed a docstring for each parameter so I can remember what each parameter is.

No files, tests, or entry points are named. Begin by locating the notebook's code-completion implementation and related tests; compare the current alphabetical parameter suggestions with the requested keyword insertion, positional ordering, and parameter docstrings, then define tests for each behavior.

Written by the indexing model from the issue text.