Bug 40067: Fix reproducibility issue in classes2.dex

We make sure our MOZ_BUILD_DATE gets used as a source for showing date
related information on the Fenix about page.

buildSrc/src/main/java/Config.kt

@@ -38,7 +38,14 @@ object Config {
 
     @JvmStatic
     fun generateBuildDate(): String {
-        val dateTime = LocalDateTime.now()
+        val dateTime = if (System.getenv("MOZ_BUILD_DATE") != null) {
+          // Converting our MOZ_BUILD_DATE to LocalDateTime
+          val format = SimpleDateFormat("yyyyMMddHHmmss", Locale.US)
+          val date = format.parse(System.getenv("MOZ_BUILD_DATE"))
+          java.sql.Timestamp(date.getTime()).toLocalDateTime()
+        } else {
+          LocalDateTime.now()
+        }
         val timeFormatter = DateTimeFormatter.ofPattern("h:mm a")
 
         return "${dateTime.dayOfWeek.toString().toLowerCase().capitalize()} ${dateTime.monthValue}/${dateTime.dayOfMonth} @ ${timeFormatter.format(dateTime)}"