Add sortpom to force consistency in pom files

This JIRA is for introducing style rules for `pom.xml` files in the Narayana code base. `SortPom` is proposed to be added alongside `Checkstyle`as the latter is not able to enforce style rules to XML files. Another nice feature of `SortPom` is that this software is able to automatically sort `pom.xml`. The main reason to introduce SortPom is to enforce consistency in `pom.xml` files