Add Comic 21 (#3721)

* Add Comic 21

* actually set `isNsfw`

src/id/comic21/build.gradle

@@ -0,0 +1,10 @@
+ext {
+    extName = 'Comic 21'
+    extClass = '.Comic21'
+    themePkg = 'mangathemesia'
+    baseUrl = 'https://comic21.me'
+    overrideVersionCode = 0
+    isNsfw = false
+}
+
+apply from: "$rootDir/common.gradle"

src/id/comic21/src/eu/kanade/tachiyomi/extension/id/comic21/Comic21.kt

@@ -0,0 +1,29 @@
+package eu.kanade.tachiyomi.extension.id.comic21
+
+import eu.kanade.tachiyomi.multisrc.mangathemesia.MangaThemesia
+import eu.kanade.tachiyomi.source.model.SManga
+import org.jsoup.nodes.Document
+
+class Comic21 : MangaThemesia(
+    "Comic 21",
+    "https://comic21.me",
+    "id",
+) {
+    override val hasProjectPage = true
+
+    override fun mangaDetailsParse(document: Document): SManga {
+        return super.mangaDetailsParse(document).apply {
+            // Add 'color' badge as a genre
+            if (document.selectFirst(".thumb .colored") != null) {
+                val genres = genre
+                    ?.split(", ")
+                    ?.toMutableList()
+                    ?: mutableListOf()
+
+                genre = genres
+                    .apply { add("Color") }
+                    .joinToString()
+            }
+        }
+    }
+}