Bug 1699394 - Improve the error reporting of the Glean cli tool

[Dexterp37]

Instead of printing the whole exception, this exclusively prints stdout and stderr.

In case of error, here's what gets printed:

npx glean glinter src/*.yaml
Checking for a Glean virtual environment at /mnt/c/Mozilla/glean.js/samples/web-extension/javascript/.venv
Using Glean virtual environment at /mnt/c/Mozilla/glean.js/samples/web-extension/javascript/.venv
ERROR running glean_parser v2.5.0

==============================================================================
/mnt/c/Mozilla/glean.js/samples/web-extension/javascript/src/metrics.yaml:
    ```
    sample: webext_started!
    ```

    'webext_started!' is not valid under any of the given schemas
        'webext_started!' does not match '^[a-z_][a-z0-9_]*$'