Exiting with a non-zero exit code causes nano to think the linter failed to run

**Is your feature request related to a problem? Please describe.**
In nano, if a linter exits with a non-zero exit code, it assumes the command has failed and aborts showing the results from the linter all-together (Instead simply displaying `[ Error invoking '' ]`, e.g. `[ Error invoking 'pylint' ]`).

**Describe the solution you’d like**
It would be helpful if pyright had a flag (or config option) similar to pylint's `--exit-zero` flag, so it can be used more easily in nano (the other option here being some form of wrapper to trash the exit code, which is not desirable since it adds unnecessary complexity).

Start by locating Pyright's command-line option and configuration handling for process exit status, then check how diagnostics are emitted when a linter-like invocation returns a non-zero code. Add a documented option or configuration setting matching the requested behavior, and verify that diagnostics remain visible while the selected invocation can exit successfully.

Written by the indexing model from the issue text.