Timesheet fixes for invalid data

[marcelfolaron]

Description

Fix timesheet data issue by disallowing adding entries in the wrong timezone.
There were several timezone collisions that could happen and those cannot be resolved automatically. As such we are disabling the ability to add additional weekday entries for timesheet rows that were added in different timezones.

Screenshot of the result

Checklist

• [ x] My code passes all test cases.
• [ x] My code passes our static analysis suite.
• [ x] My code passes our continuous integration process.

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