etc: add some missing functionality to bash completions

[grondo]

Problem: The bash tab completions are currently missing a couple things:

• the flux-queue(1) completions are missing the --queue option for a couple subcommands
• the flux-python(1) command doesn't have any completions, so you can't complete the path of a script to pass to flux python with tab.

Fix these issues.

[grondo]

Thanks! I've set MWP.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 83.36%. Comparing base (519131a) to head (687b6a0).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #6060 +/- ## =========================================== + Coverage 54.46% 83.36% +28.89% =========================================== Files 471 519 +48 Lines 76412 83818 +7406 =========================================== + Hits 41618 69873 +28255 + Misses 34794 13945 -20849 ``` [see 440 files with indirect coverage changes](https://app.codecov.io/gh/flux-framework/flux-core/pull/6060/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=flux-framework)