Applications menu: Hide Services/Templates qubes during routine app use

[RefinedSoftwareLLC]

Note: I do not know how much this overlaps with Qubes Admin API having managed Users.
Note: The goal is to provide an opt in experience, to hide options that are for installing/upgrading/configuring of any Qube/Application/dom0, during routine app use of Qubes OS. This increases security by hiding options you should not use during routine app use, while providing a minimalist experience to focus on productivity.

Qubes OS version:

R4.0

Affected component(s):

dom0's Application Menu

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Steps to reproduce the behavior:

Open dom0's Application Menu and see all qubes (except dvm-templates).

Expected behavior:

• 1. Add to Application Menu, as the first item, a "Simple Mode" checkbox (or "Minimal Mode" or "Routine Mode"). Do not name "Guest Mode" as it does not force only the use of DispVMs.

• Toggling this does not close the menu but instantly shows the new menu list.

• 2. Simple Mode: Hides "Run Program...", "Terminal Emulator", "Create Qubes VM", all "Service:" qubes, all "Template" qubes, and all "DVMTemplate" Qubes (see # 6 below).

• 3. Simple Mode: In the Application Menu, change "System Tools" to "Simple Mode System Tools", hiding all entries (even Settings Manager & Qube Manager) except: About Xfce, Accessibility, Application Finder, Backup Qubes, Display, PulseAudio Volume Control, Screenshot.

• 4. In the Application Menu, do not display <vmname>: Qube Settings inside any Qube, and if this was its only menu item, then hide the Qube completely from the Application Menu.

• 5. In Qube Manager, right click qube, Qube Settings, add checkbox "Hide during simple mode". This allows you to hide during simple mode, development/debugging/experimental Qubes you do not use routine apps on.

• 6. qvm-features appmenus-dispvm 1 shouldn't exist and is not needed.

• Instead if qvm-prefs <vmname> template_for_dispvms true then show in applications menu under both Disposable: and Template: (not Domain: but alternatively DTemplate: or DVMTemplate:)

• Template:/DVMTemplate: is used for permanent updates but not app use.

• Simple Mode: Hide this Template:/DVMTemplate: entry from the Application Menu.

Actual behavior:

dom0's Application Menu displays all qubes except dvm-templates.

[andrewdavidwong]

Somewhat related: #3910

[andrewdavidwong]

Somewhat related: #3910