Glean-parser

- Fix indentation for generated Swift code

- Created labeled metrics and events in Swift code and wrap it in a
configured namespace

- BUGFIX: `memory_unit` is now passed to the Kotlin generator.

- A new parser config, `do_not_disable_expired`, was added to turn off the
feature that expired metrics are automatically disabled. This is useful if you
want to retain the disabled value that is explicitly in the `metrics.yaml`
file.
- `glinter` will now report about superfluous `no_lint` entries.

- A `glinter` tool is now included to find common mistakes in metric naming
and setup. This check is run during `translate` and warnings will be
displayed. ⚠ These warnings will be treated as errors in a future revision.

- BUGFIX: `GleanGeckoMetricsMapping` must include `LabeledMetricType`
and `CounterMetricType`.