Add fromMnemonic using same decode method as wallet_propose (rfc1751) (#1992)

* Add rfc1751 mnemonic decoding

packages/xrpl/tsconfig.json

@@ -14,6 +14,10 @@
     "esModuleInterop": true,
     "suppressImplicitAnyIndexErrors": false,
     "resolveJsonModule": true,
-    "preserveSymlinks": true
-  }
+    "preserveSymlinks": true,
+  },
+  "include": [
+    "src/**/*.ts",
+    "src/**/*.json"
+  ]
 }