Add AnalysisPlugin interface and implementation

[chrisrueger]

Closes #6772

This pull request introduces a new AnalysisPlugin extension point to the bnd tool, allowing plugins to receive callbacks about analysis decisions—especially the reasoning behind version range choices for package imports. It provides both the interface and documentation for plugin authors, as well as comprehensive tests to ensure correct behavior and ordering.

The most important changes are:

New Plugin Extension Point

• Added the AnalysisPlugin interface in aQute.bnd.service, enabling plugins to receive notifications about version range decisions and other analysis events during the bundle analysis phase. (biz.aQute.bndlib/src/aQute/bnd/service/AnalysisPlugin.java)

Analyzer Integration

• Modified the Analyzer to call reportImportVersion() on all registered AnalysisPlugin instances whenever it determines a version range for an import, including a human-readable explanation for the decision. (biz.aQute.bndlib/src/aQute/bnd/osgi/Analyzer.java) [1] [2]

Documentation

• Added a new documentation page describing the AnalysisPlugin interface, usage examples, and typical use cases for tracking and logging analysis decisions. (docs/_plugins/analysisplugin.md)

Testing

• Introduced a comprehensive test suite for the AnalysisPlugin extension, verifying that plugins are called, receive correct version decision data, and respect plugin ordering. (biz.aQute.bndlib.tests/test/test/AnalysisPluginTest.java)