Fix/update subscription clear data loader cache (#908)

* Set updater running flag to false only at the end of the update

For clearing the data loader cache properly, the update status subscription requires the update to be running.

For the last completed manga update the flag was immediately set to false which prevented the dataloader cache from getting cleared, returning outdated data for the last updated manga

* Correctly clear the "MangaForIdsDataLoader" cache

The cache keys for this dataloader are lists of manga ids.
Thus, it is not possible to clear only the cached data of the provided manga id and instead each cache entry that includes the manga id has to be cleared

* Ensure that manga dataloader caches gets cleared during global update

The "StateFlow" drops value updates in case the collector is too slow, which was the case for the "UpdateSubscription".

This caused the dataloader cache to not get properly cleared because the running state of the update was already set to false.

server/src/main/kotlin/suwayomi/tachidesk/graphql/cache/CustomCacheMap.kt

@@ -0,0 +1,46 @@
+package suwayomi.tachidesk.graphql.cache
+
+import org.dataloader.CacheMap
+import java.util.concurrent.CompletableFuture
+
+class CustomCacheMap<K, V> : CacheMap<K, V> {
+    private val cache: MutableMap<K, CompletableFuture<V>>
+
+    init {
+        cache = HashMap()
+    }
+
+    override fun containsKey(key: K): Boolean {
+        return cache.containsKey(key)
+    }
+
+    override fun get(key: K): CompletableFuture<V> {
+        return cache[key]!!
+    }
+
+    fun getKeys(): Collection<K> {
+        return cache.keys.toSet()
+    }
+
+    override fun getAll(): Collection<CompletableFuture<V>> {
+        return cache.values
+    }
+
+    override fun set(
+        key: K,
+        value: CompletableFuture<V>,
+    ): CacheMap<K, V> {
+        cache[key] = value
+        return this
+    }
+
+    override fun delete(key: K): CacheMap<K, V> {
+        cache.remove(key)
+        return this
+    }
+
+    override fun clear(): CacheMap<K, V> {
+        cache.clear()
+        return this
+    }
+}