Rework scheduled tasks

[lafrech]

• Fix: skip campaign if enabled is False
• Add make_date_range_around_datetime
• Harmonize date range construction in check_missing / check_outliers with download_weather_data

[codecov[bot]]

Codecov Report

Patch coverage: 91.30% and project coverage change: -0.14 :warning:

Comparison is base (0a419d1) 95.70% compared to head (ea6c2cc) 95.57%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #171 +/- ## ========================================== - Coverage 95.70% 95.57% -0.14% ========================================== Files 38 38 Lines 2492 2484 -8 Branches 467 467 ========================================== - Hits 2385 2374 -11 - Misses 83 86 +3 Partials 24 24 ``` | [Impacted Files](https://codecov.io/gh/BEMServer/bemserver-core/pull/171?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BEMServer) | Coverage Δ | | |---|---|---| | [bemserver\_core/scheduled\_tasks/check\_missing.py](https://codecov.io/gh/BEMServer/bemserver-core/pull/171?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BEMServer#diff-YmVtc2VydmVyX2NvcmUvc2NoZWR1bGVkX3Rhc2tzL2NoZWNrX21pc3NpbmcucHk=) | `90.00% <90.00%> (ø)` | | | [bemserver\_core/scheduled\_tasks/check\_outliers.py](https://codecov.io/gh/BEMServer/bemserver-core/pull/171?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BEMServer#diff-YmVtc2VydmVyX2NvcmUvc2NoZWR1bGVkX3Rhc2tzL2NoZWNrX291dGxpZXJzLnB5) | `90.38% <90.00%> (ø)` | | | [bemserver\_core/scheduled\_tasks/cleanup.py](https://codecov.io/gh/BEMServer/bemserver-core/pull/171?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BEMServer#diff-YmVtc2VydmVyX2NvcmUvc2NoZWR1bGVkX3Rhc2tzL2NsZWFudXAucHk=) | `98.97% <90.90%> (-0.03%)` | :arrow_down: | | [...rver\_core/scheduled\_tasks/download\_weather\_data.py](https://codecov.io/gh/BEMServer/bemserver-core/pull/171?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BEMServer#diff-YmVtc2VydmVyX2NvcmUvc2NoZWR1bGVkX3Rhc2tzL2Rvd25sb2FkX3dlYXRoZXJfZGF0YS5weQ==) | `86.20% <90.90%> (-5.99%)` | :arrow_down: | | [bemserver\_core/time\_utils.py](https://codecov.io/gh/BEMServer/bemserver-core/pull/171?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BEMServer#diff-YmVtc2VydmVyX2NvcmUvdGltZV91dGlscy5weQ==) | `100.00% <100.00%> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BEMServer). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BEMServer)

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