Add Support for PowerMock Version 2

[dhaura]

Purpose

• PR builder with Java 11 fails due to powermock version [1]. Therefore, this PR introduce Java 11 support to the repo by bumping PowerMock to version 2.
• Bump power mock version from 1.7.4 to 2.0.9.
• Bump jacoco version from 0.7.9 to 0.8.11

[1] - https://github.com/wso2-extensions/identity-outbound-auth-x509/pull/81#issuecomment-1943545325

[jenkins-is-staging]

PR builder started Link: https://github.com/wso2/product-is/actions/runs/7911049379

[jenkins-is-staging]

PR builder completed Link: https://github.com/wso2/product-is/actions/runs/7911049379 Status: success