fix for processing#1507 - mac signing issues for release builds

fixes issue with Mac app notarization failure by signing the whole app again
after fileAssocations are made. previously, release builds were failing because
the .icns files for .pde, .pdex, and .pdez were added to the .app file after
signing.

Author: kjhollen

app/build.gradle.kts

@@ -186,7 +186,7 @@ tasks.register<Exec>("packageCustomDmg"){
     onlyIf { OperatingSystem.current().isMacOsX }
     group = "compose desktop"
 
-    dependsOn(distributable(), "installCreateDmg")
+    dependsOn("signApp", "installCreateDmg")
 
     val packageName = distributable().packageName.get()
     val dir = distributable().destinationDir.get()
@@ -590,9 +590,35 @@ tasks.register("signResources"){
         }
         file(composeResources("Info.plist")).delete()
     }
+}
 
+/* for mac, perform one final signature of the whole app before submitting
+ * the app for notarization.
+ */
+tasks.register<Exec>("signApp"){
+    onlyIf {
+        OperatingSystem.current().isMacOsX
+            &&
+        compose.desktop.application.nativeDistributions.macOS.signing.sign.get()
+    }
+
+    group = "compose desktop"
+    dependsOn("createDistributable", "setExecutablePermissions")
 
+    val packageName = distributable().packageName.get()
+    val dir = distributable().destinationDir.get()
+    val app = dir.file("$packageName.app").asFile
+
+    commandLine(
+        "codesign",
+        "--timestamp",
+        "--force",
+        "--deep",
+        "--options=runtime",
+        "--sign", "Developer ID Application",
+        app)
 }
+
 tasks.register("setExecutablePermissions") {
     description = "Sets executable permissions on binaries in Processing.app resources"
     group = "compose desktop"