feat: generate content-bound poToken

YouTube switched to using content-bound poToken, i.e. the poToken is generated
for each video using the video's ID. This fixes issues, where the server would
respond with 403, as the previously generated poToken was no longer valid.

Ref: FreeTubeApp/FreeTube#8137

Author: FineFindus

app/src/main/java/com/github/libretube/api/poToken/PoTokenGenerator.kt

@@ -19,7 +19,6 @@ class PoTokenGenerator : PoTokenProvider {
 
     private object WebPoTokenGenLock
     private var webPoTokenVisitorData: String? = null
-    private var webPoTokenStreamingPot: String? = null
     private var webPoTokenGenerator: PoTokenWebView? = null
 
 
@@ -37,10 +36,7 @@ class PoTokenGenerator : PoTokenProvider {
      * [PoTokenGenerator.getWebClientPoToken] was called
      */
     private fun getWebClientPoToken(videoId: String, forceRecreate: Boolean): PoTokenResult {
-        // just a helper class since Kotlin does not have builtin support for 4-tuples
-        data class Quadruple<T1, T2, T3, T4>(val t1: T1, val t2: T2, val t3: T3, val t4: T4)
-
-        val (poTokenGenerator, visitorData, streamingPot, hasBeenRecreated) =
+        val (poTokenGenerator, visitorData, hasBeenRecreated) =
             synchronized(WebPoTokenGenLock) {
                 val shouldRecreate = webPoTokenGenerator == null || forceRecreate || webPoTokenGenerator!!.isExpired()
 
@@ -66,22 +62,17 @@ class PoTokenGenerator : PoTokenProvider {
                         // create a new webPoTokenGenerator
                         webPoTokenGenerator = PoTokenWebView
                             .newPoTokenGenerator(LibreTubeApp.instance)
-
-                        // The streaming poToken needs to be generated exactly once before generating
-                        // any other (player) tokens.
-                        webPoTokenStreamingPot = webPoTokenGenerator!!.generatePoToken(webPoTokenVisitorData!!)
                     }
                 }
 
-                return@synchronized Quadruple(
+                return@synchronized Triple(
                     webPoTokenGenerator!!,
                     webPoTokenVisitorData!!,
-                    webPoTokenStreamingPot!!,
                     shouldRecreate
                 )
             }
 
-        val playerPot = try {
+        val poToken = try {
             // Not using synchronized here, since poTokenGenerator would be able to generate
             // multiple poTokens in parallel if needed. The only important thing is for exactly one
             // visitorData/streaming poToken to be generated before anything else.
@@ -105,13 +96,11 @@ class PoTokenGenerator : PoTokenProvider {
 
         if (BuildConfig.DEBUG) {
             Log.d(
-                TAG,
-                "poToken for $videoId: playerPot=$playerPot, " +
-                        "streamingPot=$streamingPot, visitor_data=$visitorData"
+                TAG, "poToken for $videoId: $poToken, visitor_data=$visitorData"
             )
         }
 
-        return PoTokenResult(visitorData, playerPot, streamingPot)
+        return PoTokenResult(visitorData, poToken, poToken)
     }
 
     override fun getWebEmbedClientPoToken(videoId: String?): PoTokenResult? = null