feat: Add configurable project file limit setting

[kluhan]

This PR replaces the hardcoded project preload threshold with a configurable setting.

Changes:

• Added a new setting: vscode-rpgle.projectFileLimit
• Default remains 1000 to preserve current behavior
• Server now reads this setting when loading workspace files
• Improved log message to include detected file count and configured limit when project mode is disabled

Checklist

• have tested my change
• updated relevant documentation
• Remove any/all console.logs I added
• eslint is not complaining
• have added myself to the contributors' list in the README
• for feature PRs: PR only includes one feature enhancement.