Disable renaming a Data Store while it is open in an editor

[PiispaH]

The option to rename a Data Store is disabled from the action menu while the Data Store is open.

Fixes spine-tools/Spine-Toolbox#2458

Checklist before merging

• [x] Documentation (also in Toolbox repo) is up-to-date
• [x] Release notes in Toolbox repo have been updated
• [x] Unit tests have been added/updated accordingly
• [x] Code has been formatted by black
• [x] Unit tests pass

[codecov-commenter]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (082ca23) 60.25% compared to head (cf2ff20) 60.27%.

Files	Patch %	Lines
spine_items/data_store/data_store.py	25.00%	3 Missing :warning:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## 0.8-dev #181 +/- ## =========================================== + Coverage 60.25% 60.27% +0.01% =========================================== Files 194 194 Lines 17687 17691 +4 Branches 2887 2888 +1 =========================================== + Hits 10658 10663 +5 + Misses 6462 6461 -1 Partials 567 567 ```

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