Allow to set Start/End Date in Timeline when only End/Start Date is set

Issue Summary

Allow to set Start/End Date in Timeline when only End/Start Date is set

Steps to Reproduce

1. Add only the Start or End date to an Issue
2. Try to add the End or Start date to the Issue in the Timeline View

Expected Results

The End or Start date should be added through the Timeline view

Workaround

Add the Start/End Date Fields to the Fields section of the Plan & add the values from there