[the-glu]

This PR adds two options in the benchmarker for implicit subscriptions to fix #1845:

• reuse_subscription to reuse subscriptions
• create_when_activated to request an implicit subscription only when going to the activated state.

Tested locally with minimal.jsonnet.

Parsing the report with jq -r '.report.scenarios[].operations[] | select(.type|test("(create|update)OperationalIntentReference")) | .origins[] | select(.origin|startswith("Implicit")) | .outcomes[].successful[]? | .query.request.json | "\(.state) subscription_id=\(.subscription_id != null) new_subscription=\(.new_subscription != null)"' /tmp/report | sort | uniq

Using default values:

Accepted subscription_id=false new_subscription=true
Activated subscription_id=false new_subscription=true

Enabling reuse_subscription:

Accepted subscription_id=false new_subscription=true
Activated subscription_id=true new_subscription=false

Enabling create_when_activated:

Accepted subscription_id=false new_subscription=false
Activated subscription_id=false new_subscription=true

Enabling both AND manually generating two activate actions (to have an ID to reuse):

Accepted subscription_id=false new_subscription=false
Activated subscription_id=false new_subscription=true
Activated subscription_id=true new_subscription=false

The latter enables the requested behavior in #1845.