Refactor some modules + add dependency management (still WIP)

plugins/src/main/java/io.element.android-library.gradle.kts

@@ -0,0 +1,12 @@
+import extension.androidConfig
+import extension.proguardConfig
+
+plugins {
+    id("com.android.library")
+    id("kotlin-android")
+}
+
+android {
+    androidConfig()
+    proguardConfig()
+}