Mobile: show Homepage contents and avoid duplicate menus

Summary:
After this change, the Homepage finally shows contents on Mobile,
instead of just showing the sidebar menu twice.

Closes T15216

Test Plan:
To test this change in general:

- resize the window horizontally and enjoy

I tested it in:

- tested homepage of Phorge
- Audit
- tested homepage of Audit
- Auth
- tested Auth homepage
- tested Login page
- tested Forgot your password page
- Config
- tested Config homepage
- tested page Core Settings
- tested page Unresolved Setup Issues
- (Services)
- tested page Database Status
- tested page Cache Status
- tested page Notification Servers
- tested page Repository Services
- tested page Search Servers
- (Extensions/Modules)
- tested page Constants: Differential
- tested page Content Sources
- Conpherence
- tested open-close menu
- tested persistent chat
- tested Rooms list
- tested single Chat
- Dashboards
- tested general homepage of Dashboards
- tested specific Dashboard - view page
- tested specific Dashboard - edit page
- Differential
- tested general homepage of Differential
- tested Create Diff page
- Diffusion
- tested general homepage of Diffusion
- tested specific Diffusion repository - view page
- tested specific Diffusion repository - Manage page
- tested specific Diffusion repository - Policy page
- tested specific Diffusion repository - Automation page
- tested specific commit page - view page
- tested specific commit page - Edit Commit
- Diviner
- tested general homepage of Diviner
- tested specific Diviner book
- tested list of technical Classes
- tested specific technical Class
- tested search of All Atoms
- Feed
- tested Feed homepage ("All Stories")
- tested specific feed - view page
- Files
- tested general homepage of Files
- tested specific File - view page
- tested specific File - Edit File
- tested Award Token popup
- tested Flag for Later
- tested View Transforms
- Form Engine
- tested View Forms Configurations page
- tested specific View Form Configuration
- tested Use Form
- Maniphest
- tested general homepage of Maniphest
- tested specific Maniphest Task - view page
- tested specific Maniphest Task - Edit mode
- tested specific Maniphest Task - Award Token popup
- Menu
- tested page Configure Menu
- tested page Personal Menu Items
- tested page Global Menu Items
- Notifications
- tested open action
- tested close action
- tested click action
- People
- tested general homepage of People
- tested specific User - view page
- tested specific User - Settings page - home
- tested specific User - Settings page - Date & Time
- tested specific User - Settings page - External Editor
- tested specific User - Settings page - External Editor
- tested specific User - Settings page - SSH Public Keys
- tested specific User - Settings page - SSH Public Keys - upload popup
- tested specific User - Settings page - SSH Public Keys - view history
- Pholio
- tested general homepage of Pholio
- tested Create a Mock page
- tested specific Pholio - view
- tested specific Pholio - Edit page
- tested specific Pholio - Award Token popup
- tested specific Pholio - Edit Related Tasks popup
- tested specific Pholio - add a Comment
- Phriction
- tested specific page of Phriction - view
- tested specific page of Phriction - Create Page popup
- tested specific page of Phriction - Create Page dedicated page
- tested specific page of Phriction - Edit Page
- tested specific page of Phriction - Award Token popup
- Project
- tested general homepage of Projects
- tested Create Project page
- Search
- tested search results All Results
- tested Advanced Search page
- TOTP
- tested input screen
- Workboard
- tested specific Workboard
- tested Create Task popup
- tested Add Column popup
- tested Manage Workboard page
- tested Edit Details page
- test Flag for Later popup
- test Edit Picture page

Reviewers: O1 Blessed Committers, Cigaryno, speck

Reviewed By: O1 Blessed Committers, Cigaryno, speck

Subscribers: avivey, speck, tobiaswiese, Matthew, Cigaryno

Tags: #mobile, #ux

Maniphest Tasks: T15216

Differential Revision: https://we.phorge.it/D25107