Rich exports with the real Excel format

In this issue, we'll:

• Move the export features into another (free) plugin for technical reasons: Requirement Yogi is very lightweight (1Mb) but the export library is heavy (10Mb) and used by several add-ons.

• Provide all information about requirements and their properties,

• Provide hyperlinks back to Confluence.

The add-on will be published as https://marketplace.atlassian.com/plugins/com.playsql.play-sql-export-addon, if accepted. It will also be shipped and installed by default in the RY jar.