Issue 2409 graph alternative filter

[PiispaH]

Added method to check if an item is active in a certain scenario by taking the alternative ranks into account.

Re spine-tools/Spine-Toolbox#2409

Checklist before merging

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

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 84.61538% with 2 lines in your changes missing coverage. Please review.

Project coverage is 78.23%. Comparing base (c630744) to head (f044d03). Report is 2 commits behind head on master.

Files	Patch %	Lines
spinedb_api/db_mapping.py	84.61%	0 Missing and 2 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #417 +/- ## ======================================= Coverage 78.23% 78.23% ======================================= Files 72 72 Lines 9550 9563 +13 Branches 2039 2042 +3 ======================================= + Hits 7471 7482 +11 Misses 1741 1741 - Partials 338 340 +2 ```

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