[Improve][Manager] Update base64 encoder

[aloyszhang]

Description

Now the manager encodes the token with base-64 encoder from sun.misc.BASE64Encoder in org.apache.inlong.manager.service.resource.sink.es.ElasticsearchApi

String token = String.valueOf(new BASE64Encoder().encode(tokenStr.getBytes(StandardCharsets.UTF_8)));

But sun.misc.BASE64Encoder has been removed from JDK9, so there will be an error when compiling InLong project with JDK after version 9.

[ERROR] COMPILATION ERROR : 
[INFO] -------------------------------------------------------------
[ERROR] /data1/tools/code/inlong/inlong-manager/manager-service/src/main/java/org/apache/inlong/manager/service/resource/sink/es/ElasticsearchApi.java:[42,16] cannot find symbol
  symbol:   class BASE64Encoder
  location: package sun.misc

Actually, JDK8 provides an alternative API to enable base64 encoder and decoder. https://docs.oracle.com/javase/9/docs/api/java/util/Base64.Encoder.html
https://docs.oracle.com/javase/9/docs/api/java/util/Base64.Decoder.html

So, it's better to refactor the base64 encoder and decoder with the new APIs.

InLong Component

InLong Manager

Are you willing to submit PR?

• Yes, I am willing to submit a PR!

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