Fix "Unit conversion when equivalency needed breaks contours in cubeviz"

[pllim]

Description

This pull request is to unit conversion when equivalency needed breaks contours in cubeviz. Unskips a test added in https://github.com/spacetelescope/jdaviz/pull/3204 .

Probably no need for change log since this is patching unreleased feature, I assume.

Change log entry

• [x] Is a change log needed? If yes, is it added to CHANGES.rst? If you want to avoid merge conflicts, list the proposed change log here for review and add to CHANGES.rst before merge. If no, maintainer should add a no-changelog-entry-needed label.

Checklist for package maintainer(s)

This checklist is meant to remind the package maintainer(s) who will review this pull request of some common things to look for. This list is not exhaustive.

• [x] Are two approvals required? Branch protection rule does not check for the second approval. If a second approval is not necessary, please apply the trivial label.
• [ ] Do the proposed changes actually accomplish desired goals? Also manually run the affected example notebooks, if necessary.
• [x] Do the proposed changes follow the STScI Style Guides?
• [x] Are tests added/updated as required? If so, do they follow the STScI Style Guides?
• [x] Are docs added/updated as required? If so, do they follow the STScI Style Guides?
• [x] Did the CI pass? If not, are the failures related?
• [x] Is a milestone set? Set this to bugfix milestone if this is a bug fix and needs to be released ASAP; otherwise, set this to the next major release milestone. Bugfix milestone also needs an accompanying backport label.
• [ ] After merge, any internal documentations need updating (e.g., JIRA, Innerspace)? 🐱

[pllim]

Somehow this one test makes 2 very different tracebacks. Funky.

x = array([0., 0., 0., 0., 0., 0., 0.])

    def f_la_from_f_nu(x):
>       return x / (wav.to_value(si.AA, spectral()) ** 2 / c_Aps)
E       ValueError: operands could not be broadcast together with shapes (7,) (3001,)

E       astropy.units.core.UnitConversionError: 'erg / (Hz s cm2 pix2)' and 'erg / (Angstrom s cm2 pix2)' are not convertible

[pllim]

The original exception reported in JIRA also produces ValueError: operands could not be broadcast together with shapes (7,) (3438,) (one of the exceptions from unskipped test)

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 91.66667% with 3 lines in your changes missing coverage. Please review.

Project coverage is 88.56%. Comparing base (21e9b87) to head (f6bdc8a).

Files with missing lines	Patch %	Lines
...specviz/plugins/unit_conversion/unit_conversion.py	85.71%	2 Missing :warning:
...imviz/plugins/aper_phot_simple/aper_phot_simple.py	92.30%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #3207 +/- ## ========================================== + Coverage 88.51% 88.56% +0.04% ========================================== Files 125 125 Lines 18694 18719 +25 ========================================== + Hits 16547 16578 +31 + Misses 2147 2141 -6 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[pllim]

@cshanahan1 , I tried to explain at https://github.com/spacetelescope/jdaviz/pull/3207#pullrequestreview-2341568057 but in case that is not clear enough, when one sets uc_plg.flux_unit = flux_unit, glue invokes this:

https://github.com/spacetelescope/jdaviz/blob/21e9b87310bfa366c38ddfc944202b41fc80ffff/jdaviz/app.py#L94

You can see at https://github.com/glue-viz/glue/blob/main/glue/core/units.py that the converter has no access to app state or data. Therefore, the fix I used is to use https://docs.astropy.org/en/stable/api/astropy.units.set_enabled_equivalencies.html#astropy.units.set_enabled_equivalencies to pass in the equivalencies to global Python state so Jdaviz unit conversion can pick them up. It is used as context manager to hopefully only enable those equivalencies when needed.

Does this make sense?

[pllim]

Ignore devdeps failure, it is unrelated.