Tab swiping: Add a subfeature flag (#5844)

Task/Issue URL:
https://app.asana.com/0/414730916066338/1209846575622295/f

### Description

This PR adds a subfeature flag `onForInternalUsers` and
`onForExternalUsers` (the feature flag for prod users to enable staged
rollout).

The flag is used inside a `SwipingTabsFeatureProvider` wrapper so
nothing else should be affected. The original flag feature flag will be
used to keep the feature enabled for all internal users.

After this, the updated privacy config will look like this:
```
"swipingTabs": {
    "state": "enabled",
    "minSupportedVersion": 52271000,
    "features": {
        "onForInternalUsers": {
            "state": "internal"
        },
        "onForExternalUsers": {
            "state": "enabled",
            "rollout": {
                "steps": [
                    {
                        "percent": 20
                    }
                ]
            }
        }
    }
}
```

### Steps to test this PR

_Internal test_
- [x] Replace the privacy config URL to:
`https://jsonblob.com/api/1356597958694592512`
- [x] Run the app using an internal build
- [x] Verify the tab swiping is working

Author: 0nko

app/src/androidTest/java/com/duckduckgo/app/browser/BrowserTabViewModelTest.kt

@@ -543,6 +543,7 @@ class BrowserTabViewModelTest {
         MockitoAnnotations.openMocks(this)
 
         swipingTabsFeature.self().setRawStoredState(State(enable = true))
+        swipingTabsFeature.onForInternalUsers().setRawStoredState(State(enable = true))
 
         db = Room.inMemoryDatabaseBuilder(context, AppDatabase::class.java)
             .allowMainThreadQueries()

app/src/main/java/com/duckduckgo/app/browser/SwipingTabsFeature.kt

@@ -25,6 +25,15 @@ import com.duckduckgo.feature.toggles.api.Toggle
     featureName = "swipingTabs",
 )
 interface SwipingTabsFeature {
+    // The main kill switch for the feature
     @Toggle.DefaultValue(false)
     fun self(): Toggle
+
+    // The toggle used to enable the feature for internal users
+    @Toggle.DefaultValue(false)
+    fun onForInternalUsers(): Toggle
+
+    // The toggle used to enable the feature for external users
+    @Toggle.DefaultValue(false)
+    fun onForExternalUsers(): Toggle
 }

app/src/main/java/com/duckduckgo/app/browser/SwipingTabsFeatureProvider.kt

@@ -25,6 +25,7 @@ class SwipingTabsFeatureProvider @Inject constructor(
     swipingTabsFeature: SwipingTabsFeature,
 ) {
     val isEnabled: Boolean by lazy {
-        swipingTabsFeature.self().isEnabled()
+        swipingTabsFeature.self().isEnabled() &&
+            (swipingTabsFeature.onForInternalUsers().isEnabled() || swipingTabsFeature.onForExternalUsers().isEnabled())
     }
 }

app/src/test/java/com/duckduckgo/app/browser/BrowserViewModelTest.kt

@@ -111,6 +111,7 @@ class BrowserViewModelTest {
 
         configureSkipUrlConversionInNewTabState(enabled = true)
         swipingTabsFeature.self().setRawStoredState(State(enable = false))
+        swipingTabsFeature.onForInternalUsers().setRawStoredState(State(enable = true))
 
         whenever(mockDefaultBrowserPromptsExperiment.commands).thenReturn(defaultBrowserPromptsExperimentCommandsFlow.receiveAsFlow())
 

app/src/test/java/com/duckduckgo/app/tabs/ui/TabSwitcherViewModelTest.kt

@@ -134,6 +134,7 @@ class TabSwitcherViewModelTest {
         MockitoAnnotations.openMocks(this)
 
         swipingTabsFeature.self().setRawStoredState(State(enable = true))
+        swipingTabsFeature.onForInternalUsers().setRawStoredState(State(enable = true))
 
         whenever(mockTabRepository.flowDeletableTabs)
             .thenReturn(repoDeletableTabs.consumeAsFlow())