Rework HBox-based pages and account settings

- Refactor everything about HBox, and adapt all the pages and popups
  that used it

- Replace HTabContainer by HTabbedBox

- Make boxes swippable

- Make esc presses in boxes click the cancel button

- Make all boxes and popups scrollable when needed

- Replace generic apply button icons in popups

- Fix tab focus for error and invite popups

- Rework (still WIP) the account settings page:
  - Use the standard tabbed design of other pages
  - Ditch the horizontal profile layout, hacky and impossible to extend
  - Add real-time coloring for the display name field

- Implement a device list in account settings (Sessions, still WIP)

src/gui/Pages/Chat/ChatPage.qml

@@ -11,6 +11,7 @@ import "Timeline"
 HColumnPage {
     id: chatPage
     padding: 0
+    column.spacing: 0
 
     onLoadEventListChanged: if (loadEventList) loadedOnce = true
     Component.onDestruction: if (loadMembersFuture) loadMembersFuture.cancel()

src/gui/Pages/Chat/RoomPane/MemberDelegate.qml

@@ -67,10 +67,7 @@ HTile {
                 roomId: chat.roomId,
                 targetUserId: model.id,
                 targetDisplayName: model.display_name,
-                operation:
-                    model.invited ?
-                    RemoveMemberPopup.Operation.Disinvite :
-                    RemoveMemberPopup.Operation.Kick,
+                operation: model.invited ? "disinvite" : "kick",
             })
 
             Component.onCompleted: py.callClientCoro(
@@ -94,7 +91,7 @@ HTile {
                 roomId: chat.roomId,
                 targetUserId: model.id,
                 targetDisplayName: model.display_name,
-                operation: RemoveMemberPopup.Operation.Ban,
+                operation: "ban",
             })
 
             Component.onCompleted: py.callClientCoro(

src/gui/Pages/Chat/RoomPane/SettingsView.qml

@@ -57,9 +57,6 @@ HFlickableColumnPage {
     }
 
 
-    useVariableSpacing: false
-    column.spacing: theme.spacing * 1.5
-
     flickShortcuts.active:
         ! mainUI.debugConsole.visible && ! chat.composerHasFocus
 
@@ -82,6 +79,8 @@ HFlickableColumnPage {
         }
     }
 
+    Keys.onEscapePressed: cancel()
+
 
     HRoomAvatar {
         id: avatar