Add Konsist test to check that toPersistentList() is not used.

Same for `toPersistentSet()` and `toPersistentMap()`.
Fix existing issues.

tests/konsist/src/test/kotlin/io/element/android/tests/konsist/KonsistImmutableTest.kt

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2023, 2024 New Vector Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.tests.konsist
+
+import com.lemonappdev.konsist.api.Konsist
+import com.lemonappdev.konsist.api.ext.list.withoutName
+import com.lemonappdev.konsist.api.verify.assertFalse
+import org.junit.Test
+
+class KonsistImmutableTest {
+    /**
+     * toPersistentList() returns a PersistentList which allow mutations, while toImmutableList() returns
+     * an ImmutableList which does not allow mutations. Generally, we do not use the mutation features,
+     * so we should prefer toImmutableList.
+     */
+    @Test
+    fun `toPersistentList() should not be used instead of toImmutableList()`() {
+        Konsist
+            .scopeFromProject()
+            .functions()
+            .withoutName("toPersistentList() should not be used instead of toImmutableList()")
+            .assertFalse(additionalMessage = "Please use toImmutableList() instead of toPersistentList()") {
+                it.text.contains(".toPersistentList()")
+            }
+    }
+
+    /**
+     * toPersistentSet() returns a PersistentSet which allow mutations, while toImmutableSet() returns
+     * an ImmutableSet which does not allow mutations. Generally, we do not use the mutation features,
+     * so we should prefer toImmutableSet.
+     */
+    @Test
+    fun `toPersistentSet() should not be used instead of toImmutableSet()`() {
+        Konsist
+            .scopeFromProject()
+            .functions()
+            .withoutName("toPersistentSet() should not be used instead of toImmutableSet()")
+            .assertFalse(additionalMessage = "Please use toImmutableSet() instead of toPersistentSet()") {
+                it.text.contains(".toPersistentSet()")
+            }
+    }
+
+    /**
+     * toPersistentMap() returns a PersistentMap which allow mutations, while toImmutableMap() returns
+     * an ImmutableMap which does not allow mutations. Generally, we do not use the mutation features,
+     * so we should prefer toImmutableMap.
+     */
+    @Test
+    fun `toPersistentMap() should not be used instead of toImmutableMap()`() {
+        Konsist
+            .scopeFromProject()
+            .functions()
+            .withoutName("toPersistentMap() should not be used instead of toImmutableMap()")
+            .assertFalse(additionalMessage = "Please use toImmutableMap() instead of toPersistentMap()") {
+                it.text.contains(".toPersistentMap()")
+            }
+    }
+}