Add support for Exclusion Lists for Java Linter

Currently the Java Linter for this extension is scanning all of my project's autogenerated code which is causing 1000+ problems to be reported. From a very thorough investigation both VSCode and this extension do not have any exclusion options for what directories/files are scanned by the Java Linter and reported in the Problems tab.

Environment

• Operating System: Windows 10 64-bit
• JDK version: JDK 11
• Visual Studio Code version: 1.66
• Java extension version: 1.7.0

Steps To Reproduce

1. Create a Java Project and have the extension installed.
2. Write example code that would get scanned by linter with problems.
3. Review extension settings and there is no option to add exclusion for the linter.

Current Result

Java Linter scans every directory and file for the entire project with no options for exclusions, turning off linter completely or other common options.

Expected Result

Java Linter should have settings in this extension for exclusions, turning off the linter, and using the .gitignore file as a default exclusion list.

Additional Informations

VSCode has said in other issues where this is brought up that this is the responsibly of the extensions to support exclusion lists for the Problems tab. Issue that is closed talking about this is found here: https://github.com/microsoft/vscode/issues/22289

No implementation files or tests are identified in the issue. Start by locating the Java linter entry point and extension settings, then trace how diagnostics reach the Problems tab; done means exclusions, disabling, and .gitignore-based filtering are defined and verified for the reported autogenerated-code scenario.