Implement DepClean Gradle plugin and add support for multi-module project analysis

Currently, DepClean has a plugin that analyzes maven-based java projects, but we can't use it in Gradle-based java projects. The main aim of this project is to implement a DepClean Gradle plugin like DepClean maven plugin that will analyze Gradle-based java projects too. Also, the existing maven plugin may misbehave in a multi-module project analysis as it analyzes only one module at a time. So, this project also aims to make the plugin able to analyze multi-module projects such that a combined analysis will be carried out on all the modules.