Add localfs and localfsMap to the debugger configuration schema

[eyupcanakman]

Motivation

Closes #3597. Setting localfsMap (or localfs) in a ruby_lsp debug configuration shows a "Property not allowed" warning in VS Code, even though the option works. The extension forwards the launch configuration to the Ruby debug gem, which reads these keys, but they were never declared in the debugger schema, so VS Code treated them as unknown.

Implementation

Declare localfs and localfsMap under both launch and attach in the debugger configurationAttributes. The gem's DAP server reads both keys for both request types in server_dap.rb, so VS Code no longer flags them.

Automated Tests

None. The new entries are declarations in the contributes.debuggers schema in package.json, which VS Code validates against launch.json at runtime. The extension does not have tests covering its package.json contributions.

Manual Tests

1. Open a Ruby project and add a launch.json with a ruby_lsp attach configuration containing "localfsMap": "/remote:/local" (or "localfs": true).
2. On main, VS Code flags the property with "Property localfsMap not allowed".
3. With this branch, the warning is gone and the property is accepted.

[eyupcanakman]

I have signed the CLA!