[feature]: Improvement sub tasks

[Dev-A-Line]

Is there an existing issue for this?

• [X] I have searched the existing issues

Summary

1. Add the ability to create sub-tasks in non-full screen mode.
2. Add the ability to create multiple subtasks.
3. Add progress bar to the progress bar of sub tasks. 4.Change the format of displaying sub tasks. So that they are displayed inside the parent

Why should this be worked on?

Adding these elements will improve the experience of using plane many times over

[gchanchal]

Hey @Dev-A-Line , thanks for the writing your feedback. We are on-board with you and these things are already planned in the product. These will be live in forthcoming releases, stay tuned!!