Find alternative to HTMLParser library

[reckart]

Describe the refactoring action
The HTMLParser library used by ruta has not been maintained for over 10 years and is compiled with a very old Java version. It should be replaced by a modern and maintained dependency. JSoup would come to mind.

Expected benefit

• Use maintained dependencies.
• Also, this should fix an issue with using Ruta in OSGI environments related to https://issues.apache.org/jira/browse/ARIES-1219