Added extract signature task

app/build.gradle

@@ -403,6 +403,13 @@ task downloadPSL(type: Download) {
     overwrite true
 }
 
+task extractSignature(type: Exec) {
+    workingDir "${rootDir}"
+    // sudo apt install apksigcopier
+    commandLine 'sh', '-c', 'mkdir -p metadata/eu.faircode.email/signatures/' + getVersionCode() + ' &&' +
+            'apksigcopier extract --v1-only=auto app/build/outputs/apk/fdroid/release/FairEmail-v1.' + getVersionCode() + getRevision() + '-fdroid-release.apk metadata/eu.faircode.email/signatures/' + getVersionCode()
+}
+
 task upload() {
     // ./gradlew upload -Ptarget=play-preview
     doLast {