Support for Custom tsconfig in directus-extension build to Exclude Test Files

Hi team,
Currently, the directus-extension build command does not allow specifying a custom TypeScript config (like tsconfig.build.json). This makes it difficult to include test files for linting and editor support (in tsconfig.json), while excluding them from the build and published output. Many TypeScript projects solve this by using a separate build config with "exclude" for tests, but this workflow isn’t possible with the current CLI.

Could you consider adding support for a --tsconfig flag or an environment variable to let us choose which tsconfig is used for the build? This would make it much easier to maintain clean builds and follow common TypeScript project practices.

Thank you for considering this improvement!