Implement custom tab handling for app links in BrowserTabViewModel. (#6866)

Task/Issue URL:
https://app.asana.com/1/137249556945/project/488551667048375/task/1211450043710855?focus=true

### Description

Added support for better handling app links in custom tabs. When an app
link is opened in a custom tab, the app will now directly open the app
link without showing the app link prompt, regardless of the user's app
link prompt settings.

### Steps to test this PR

_App Links in Custom Tabs_
- [x] Install from this branch.
- [x] See
https://app.asana.com/1/137249556945/task/1211450043710855/comment/1211477223443413?focus=true
for steps and credentials.
- [x] See attached video to understand the flow and prerequisites (DDG
is custom tab and DDG -> Settings -> Permissions -> Open Links is Apps
is set to either `Ask Every Time` or `Never`).

_Regular App Links_
- [x] Install from this branch.
- [x] Open the app and set prerequisites: DDG is custom tab and DDG ->
Settings -> Permissions -> Open Links is Apps is set to either `Ask
Every Time` or `Never`.
- [x] Navigate to a page with an app link. I.e:
https://play.google.com/store/apps/details?id=com.duckduckgo.mobile.android&hl=en-US
- [x] Verify that you are prompted to open the link in the Play Store
app.

### UI changes
No UI changes, only behavior changes in Custom Tab for app links.

Author: anikiki

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

@@ -3820,6 +3820,18 @@ class BrowserTabViewModelTest {
         assertCommandIssued<Command.OpenAppLink>()
     }
 
+    @Test
+    fun whenHandleAppLinkCalledAndCustomTabIsTrueThenOpenAppLink() {
+        val urlType = SpecialUrlDetector.UrlType.AppLink(uriString = exampleUrl)
+        testee.setIsCustomTab(true)
+        testee.handleAppLink(urlType, isForMainFrame = true)
+        whenever(mockAppLinksHandler.isUserQuery()).thenReturn(false)
+        whenever(ctaViewModelMockSettingsStore.showAppLinksPrompt).thenReturn(false)
+        verify(mockAppLinksHandler).handleAppLink(eq(true), eq(exampleUrl), eq(false), eq(true), appLinkCaptor.capture())
+        appLinkCaptor.lastValue.invoke()
+        assertCommandIssued<Command.OpenAppLink>()
+    }
+
     @Test
     fun whenHandleNonHttpAppLinkCalledThenHandleNonHttpAppLink() {
         val urlType = SpecialUrlDetector.UrlType.NonHttpAppLink("market://details?id=com.example", Intent(), exampleUrl)

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

@@ -1031,6 +1031,7 @@ class BrowserTabFragment :
 
         if (savedInstanceState == null) {
             viewModel.onViewReady()
+            viewModel.setIsCustomTab(tabDisplayedInCustomTabScreen)
             messageFromPreviousTab?.let {
                 processMessage(it)
             }

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

@@ -588,6 +588,7 @@ class BrowserTabViewModel @Inject constructor(
     private var isProcessingTrackingLink = false
     private var isLinkOpenedInNewTab = false
     private var allowlistRefreshTriggerJob: Job? = null
+    private var isCustomTabScreen: Boolean = false
 
     private val fireproofWebsitesObserver =
         Observer<List<FireproofWebsiteEntity>> {
@@ -802,6 +803,10 @@ class BrowserTabViewModel @Inject constructor(
         initialUrl?.let { buildSiteFactory(it, stillExternal = isExternal) }
     }
 
+    fun setIsCustomTab(isCustomTab: Boolean) {
+        this.isCustomTabScreen = isCustomTab
+    }
+
     fun onViewReady() {
         url?.let {
             onUserSubmittedQuery(it)
@@ -3062,11 +3067,16 @@ class BrowserTabViewModel @Inject constructor(
     }
 
     private fun appLinkClicked(appLink: AppLink) {
-        if (appSettingsPreferencesStore.showAppLinksPrompt || appLinksHandler.isUserQuery()) {
-            command.value = ShowAppLinkPrompt(appLink)
-            appLinksHandler.setUserQueryState(false)
-        } else {
-            command.value = OpenAppLink(appLink)
+        when {
+            // When in custom tab, always open the app link directly, without prompting.
+            isCustomTabScreen -> command.value = OpenAppLink(appLink)
+
+            appSettingsPreferencesStore.showAppLinksPrompt || appLinksHandler.isUserQuery() -> {
+                command.value = ShowAppLinkPrompt(appLink)
+                appLinksHandler.setUserQueryState(false)
+            }
+
+            else -> command.value = OpenAppLink(appLink)
         }
     }