[web] Move web/apps directory to web/modals/apps
Moving files that correspond to the Apps tab, because according to the new designs the tab is supposed to be changed into a modal. But not that much of the current code will be changed, so to
make the review easier I'm moving the code first, an will change it later.
Test Plan: Run web app, checked that pressing the "+" button in the top bar still opoent the Apps tab, and it displays and works properly.
Reviewers: kamil, bartek, kuba
Reviewed By: bartek
Subscribers: ashoat, tomek, atul
Differential Revision: https://phab.comm.dev/D6811