Add sentry to django backend

[fliepeltje]

No description provided.

[BeritJanssen]

Sorry for yet another change request, but will this mean we cannot override the values that are set here? Perhaps the best place for this would be in backend.manage.main(), right after the os.environ.setdefault.... Then the common_settings would have:

SENTRY_DSN = os.getenv('SENTRY_DSN')
SENTRY_ENABLE_TRACING = True
SENTRY_SAMPLE_RATE = 1.0
SENTRY_TRACES_SAMPLE_RATE = 1.0

And manage.py:

if SENTRY_DSN:
   sentry_sdk.init(
      dsn=SENTRY_DSN,
      enable_tracing=SENTRY_ENABLE_TRACING,
      sample_rate=SENTRY_SAMPLE_RATE,
      traces_sample_rate=SENTRY_TRACES_SAMPLE_RATE
)

That way, we would be able to set different values for enable_tracing etc. per instance, but keep a Sentry init for all instances.

[BeritJanssen]

No need to add emtpy lines here.

[BeritJanssen]

I added a branch in the deployment module which should make it easier to add Sentry to the different RSLab applications. So it's not necessary to include this in the code base of the individual repos.