fix(plugin-chart-country-map): add plugin reference + json include in root tsconfig

The plugin imports src/data/manifest.json. The plugin's own tsconfig
already had resolveJsonModule + json in include after the previous fix,
but the root superset-frontend/tsconfig.json (which tsc --build walks)
also needs to resolve the manifest.json across the lib/ and esm/ babel
outputs. Add the explicit json glob and register the plugin as a
project reference so tsc finds it in build mode.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>