Refactor some modules + add dependency management (still WIP)

libraries/matrix/build.gradle

@@ -0,0 +1,35 @@
+plugins {
+    id 'com.android.library'
+    id 'org.jetbrains.kotlin.android'
+}
+
+android {
+    namespace 'io.element.android.x.sdk.matrix'
+    compileSdk 33
+
+    defaultConfig {
+        minSdk 29
+        targetSdk 33
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = '1.8'
+    }
+}
+
+dependencies {
+    api(name: 'matrix-rust-sdk', ext: 'aar')
+    implementation "net.java.dev.jna:jna:5.10.0@aar"
+    implementation 'androidx.datastore:datastore-core:1.0.0'
+    implementation 'androidx.datastore:datastore-preferences:1.0.0'
+}