Barcode scanner updates (#562)

* Add BUILDING.md

* Replace scaning library

- Out with qr_code_scanner
- In with flutter_zxing

* Update specs for jdk / kotlin / gradle

- NFI what this all means?

* Refactor barcode scanning widget

* Refactor barcode overlay

* Add handlers

* Update release notes

* Fix AppBar color

* Enhance attachment widget

* remove unused import

* Improved icon

* Select theme from main drawer

android/app/build.gradle

@@ -31,6 +31,16 @@ if (keystorePropertiesFile.exists()) {
 android {
     compileSdkVersion 34
 
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_17
+        targetCompatibility JavaVersion.VERSION_17
+    }
+
+    // If using Kotlin
+    kotlinOptions {
+        jvmTarget = JavaVersion.VERSION_17
+    }
+
     sourceSets {
         main.java.srcDirs += 'src/main/kotlin'
     }