Evaluate alternative for Nashorn and bring that as the scripting engine to execute Adaptive Scripts

[shanggeeth]

As the Nashorn was deprecated[1] with the JDK 11, the adaptive authentication script engine needs to be changed to another engine to run the Adaptive authentication scripts.

[1] http://openjdk.java.net/jeps/335

Description

• As mentioned above Nashorn is deprecated in JDK 11 and removed in JDK 15.

• Even though, WSO2 Identity Server from 6.0, employ OpenJDK Nashorn which is maintained as a standalone offering of deprecated Nashorn, it not actively maintained (supporting latest ES specifications, actively fixing bugs).

• The proposed solution is to find an alternative script engine and replace Nashorn.

[shanggeeth]

Related PRs:

• Framework changes to add GraalJS as script Engine
  Add GraalJS based script engine implementation carbon-identity-framework#5279
• Support GraalJS for conditional authentication functions
  Add GraalJS support for conditional authentication functions wso2-extensions/identity-conditional-auth-functions#152
• Run integration tests for GraalJS
  Add integration tests for GraalJS based adaptive authentication script execution #19434
• Set GraalJS as default Identity Server Engine
  Set GraalJS as default script engine carbon-identity-framework#5724
• Handle complex JSON payloads for Call Choreo function and call Analytics function wso2-extensions/identity-conditional-auth-functions#187