Fix timetracking table colums

[MichaelBuessemeyer]

This PR fixes the timetracking columns not being rendered by two angles:

1. Refactor the columns into an array of objects and pass this to the FixedExpandableTable, which is the new way of how to write columns for antd table.
2. Fix the FixedExpandableTable to still work with columns being passed as children. In the previous version, it always had an array of empty column props which likely took precedence of the passed children column props to FixedExpandableTable and thus the children column props were ignored and 0 columns were rendered instead.

URL of deployed dev instance (used for testing):

• https://___.webknossos.xyz

Steps to test:

• Do some tracing
• Open the time tracking view. It should render all expected columns

TODOs:

• Check whether point 2. is acutally fixed by this PR.

Issues:

• No issue exists for this

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(Please delete unneeded items, merge only when none are left open)

• Updated changelog

[dieknolle3333]

the code looks good to me, I only have two minor comments. feel free to resolve them if you think the fixes are unnecessary. thanks for looking into this!