Implement timetrace create record command

[dominikbraun]

Sometimes, it would make sense to directly "insert" a new record with a given time span instead of fiddling around with timetrace edit record on existing records.

To do so, a timetrace create record command is needed. I have the following syntax in mind:

timetrace create record <PROJECT KEY> {<YYYY-MM-DD>|today|yesterday} <HH-MM> <HH-MM>

Important: This command should check for collisions with other records, so probably all records from that date have to be loaded and checked internally.

[FelixTheodor]

I would like to work on this one! :)