Don't trace OPTIONS and HEAD in WSGI frameworks by default

[antonpirker]

Make sure that frameworks based on WSGI do not create transactions for the HTTP methods OPTIONS and HEAD by default.

For Django and Flask also add a config option to the integrations to specify which HTTP methods to create transactions for.

(For other smaller frameworks we keep the default of not creating OPTIONS and HEAD transaction, but will add an option to specify for wich HTTP methods to create transactions on request)

Docs PR:
getsentry/sentry-docs#11348