[storage] update package version to 12.20.0 (Azure#26303)

There are still inconsistent package versions in some places. This PR
updates them all to `12.20.0`

Author: jeremymeng

sdk/storage/storage-blob/src/generated/src/storageClient.ts

@@ -1,7 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 
-export const SDK_VERSION: string = "12.13.0";
+export const SDK_VERSION: string = "12.20.0";
 export const SERVICE_VERSION: string = "2021-10-04";
 
 export const BLOCK_BLOB_MAX_UPLOAD_BLOB_BYTES: number = 256 * 1024 * 1024; // 256MB

sdk/storage/storage-blob/src/utils/constants.ts

@@ -21,7 +21,7 @@ add-credentials: false
 core-http-compat-mode: true
 use-extension:
   "@autorest/typescript": "latest"
-package-version: 12.13.0
+package-version: 12.20.0
 ```
 
 ## Customizations for Track 2 Generator

sdk/storage/storage-blob/swagger/README.md

@@ -1,7 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 
-export const SDK_VERSION: string = "12.12.0";
+export const SDK_VERSION: string = "12.20.0";
 export const SERVICE_VERSION: string = "2021-12-02";
 
 export const KB: number = 1024;

sdk/storage/storage-file-datalake/src/generated/src/storageClient.ts

@@ -20,8 +20,8 @@ disable-async-iterators: true
 core-http-compat-mode: true
 add-credentials: false
 use-extension:
-  "@autorest/typescript": "6.0.0-rc.8"
-package-version: 12.12.0
+  "@autorest/typescript": "6.0.0"
+package-version: 12.20.0
 ```
 
 ## Customizations for Track 2 Generator