Add parent name to subchannels and sidebars modals

Summary:
Issue: https://linear.app/comm/issue/ENG-2547/restyle-sidebarlistmodal-and-subchannelslistmodal
Desing issue: https://linear.app/comm/issue/DES-20/designs-for-subchannels-modal
Adding parent name pill in the modals header

Test Plan: Run ios simulator, check that name displays correctly for short na long names in both subchannels modal and in sidebars modal

Reviewers: przemek, bartek, tomek

Reviewed By: bartek, tomek

Subscribers: ashoat, tomek, atul

Differential Revision: https://phab.comm.dev/D6209