[web] Add save functionality to the create role modal
Summary:
This adds functionality to the Create button in the create-role modal, where clicking it will save the role and close the modal. Error handling for a duplicate role name will come later in the stack
Depends on D8594
Test Plan:
Confirmed that a new role is created when the button is clicked
Reviewers: atul, ginsu
Reviewed By: atul
Subscribers: ashoat, tomek
Differential Revision: https://phab.comm.dev/D8595