Introducing the Jenkins to Bitbucket Pipelines migration tool

Introduces an open-source, automated tool to convert declarative Jenkins files into Bitbucket Pipelines YAML syntax. The tool translates common Jenkins features, marks unconverted elements for manual review, and is extensible to support custom Jenkins plugins and functionality through custom translation logic. This complements existing guides and aims to simplify the migration process from Jenkins to Bitbucket Pipelines.