Add more ways to get bintray_key

buildSrc/src/main/kotlin/upload/Bintray.kt

@@ -22,6 +22,12 @@ object Bintray {
             return bintray_user
         }
 
+        kotlin.runCatching {
+            @Suppress("UNUSED_VARIABLE", "LocalVariableName")
+            val bintray_user: String by project.rootProject
+            return bintray_user
+        }
+
         System.getProperty("bintray_user", null)?.let {
             return it.trim()
         }
@@ -53,6 +59,12 @@ object Bintray {
             return bintray_key
         }
 
+        kotlin.runCatching {
+            @Suppress("UNUSED_VARIABLE", "LocalVariableName")
+            val bintray_key: String by project.rootProject
+            return bintray_key
+        }
+
         System.getProperty("bintray_key", null)?.let {
             return it.trim()
         }