prevent mixup of account timelines (#4599)

This does 2 things:

- Removes `AccountSwitchInterceptor`, the main culprit for the bug. APIs
can no longer change their base url after they have been created. As a
result they are not Singletons anymore.
- Additionally, I refactored how MainActivity handles Intents to make it
less likely to have multiple instances of it active.

Here is how I could reliably reproduce the bug:

- Be logged in with account A and B
- Write a post with account A, cancel it before it sends (go into flight
mode for that)
- Switch to account B
- Open the "this post failed to send" notification from account A,
drafts will open
- Go back. You are in the MainActivity of account A, everything seems
fine.
- Go back again. You are in the old, now broken MainActivity of account
B. It uses the database of account B but the network of account A.
Refreshing will show posts from A.

closes #4567 
closes #4554
closes #4402 
closes #4148
closes #2663
and possibly #4588

app/src/main/java/com/keylesspalace/tusky/MainActivity.kt

@@ -363,6 +363,11 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
         }
     }
 
+    override fun onDestroy() {
+        cacheUpdater.stop()
+        super.onDestroy()
+    }
+
     /** Handle an incoming Intent,
      * @returns true when the intent is coming from an notification and the interface should show the notification tab.
      */
@@ -390,6 +395,8 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
         val accountRequested = tuskyAccountId != -1L
         if (accountRequested && tuskyAccountId != activeAccount.id) {
             accountManager.setActiveAccount(tuskyAccountId)
+            changeAccount(tuskyAccountId, intent, withAnimation = false)
+            return false
         }
 
         val openDrafts = intent.getBooleanExtra(OPEN_DRAFTS, false)
@@ -567,7 +574,6 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
             }
         }
         startActivity(composeIntent)
-        finish()
     }
 
     private fun setupDrawer(
@@ -985,11 +991,17 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
         return false
     }
 
-    private fun changeAccount(newSelectedId: Long, forward: Intent?) {
+    private fun changeAccount(
+        newSelectedId: Long,
+        forward: Intent?,
+        withAnimation: Boolean = true
+    ) {
         cacheUpdater.stop()
         accountManager.setActiveAccount(newSelectedId)
         val intent = Intent(this, MainActivity::class.java)
-        intent.putExtra(OPEN_WITH_EXPLODE_ANIMATION, true)
+        if (withAnimation) {
+            intent.putExtra(OPEN_WITH_EXPLODE_ANIMATION, true)
+        }
         if (forward != null) {
             intent.type = forward.type
             intent.action = forward.action
@@ -1240,6 +1252,7 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
         fun accountSwitchIntent(context: Context, tuskyAccountId: Long): Intent {
             return Intent(context, MainActivity::class.java).apply {
                 putExtra(TUSKY_ACCOUNT_ID, tuskyAccountId)
+                flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
             }
         }
 
@@ -1286,7 +1299,6 @@ class MainActivity : BottomSheetActivity(), ActionButtonActivity, MenuProvider {
         fun redirectIntent(context: Context, tuskyAccountId: Long, url: String): Intent {
             return accountSwitchIntent(context, tuskyAccountId).apply {
                 putExtra(REDIRECT_URL, url)
-                flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
             }
         }