Prevent JDTLS from generating metadata files at project root

[tartarughina]

Address #178

Add -Djava.import.generatesMetadataFilesAtProjectRoot=false system property to stop .project, .classpath, and .settings/ files from being created in the project directory.

This change follows the steps of other java extensions.

References:

1. JDTLS changes - Stop generating metadata files at project's root eclipse-jdtls/eclipse.jdt.ls#1900
2. Any way to get rid of .project .classpath .settings/ files? - Any way to get rid of .project .classpath .settings/ files? redhat-developer/vscode-java#618
3. Say goodbye to ".project" files in Language Support for Java 1.1.0 - https://devblogs.microsoft.com/java/say-goodbye-to-project-files-in-1-1-0/

[MaddyGuthridge]

I have tested on my machine (NixOS 25.11) and can confirm that this is working!