Add salt for MD5MaskAlgorithm and MD5EncryptAlgorithm and adjust document and proxy config-mask.yaml

[strongduanmu]

Ref #22759.

Changes proposed in this pull request:

• Add salt for MD5MaskAlgorithm and MD5EncryptAlgorithm
• adjust document and proxy config-mask.yaml
• add unit test

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• My code follows the code of conduct of this project.
• I have self-reviewed the commit code.
• I have (or in comment I request) added corresponding labels for the pull request.
• I have passed maven check locally : ./mvnw clean install -B -T1C -Dmaven.javadoc.skip -Dmaven.jacoco.skip -e.
• I have made corresponding changes to the documentation.
• I have added corresponding unit tests for my changes.