Allow configuration of hours in a working day

### Description of the issue

At my workplace, we count a day as 6 hours. I'd like to be able to configure this as currently it's working on an 8-hour day assumption.

### Your environment

* Huly desktop
* Version 0.6.343 (0.6.343)
* Apple M1 Pro / OS 14.6

### Steps to reproduce

1. Add 12 hours as an Estimate for a task
2. Note it gets converted to 1 day 4 hours after pressing enter.

### Expected behaviour

1. I can configure hours per work day in my workspace settings to 6 hours
2. 12 hours would then display as 2 days

### Actual behaviour

### Possible solutions