Add javax.activation dependency to wso2-general-project-plugin

[PasanT9]

Purpose

$subject
Fix test failures in wso2ei-6.6.0 scenario tests.
Java 9 and above doesn't contain javax.activation library by default. Thus need to add the following dependency.

<dependency>
     <groupId>com.sun.activation</groupId>
     <artifactId>javax.activation</artifactId>
     <version>1.2.0</version>
</dependency>