Extract Active Job metadata earlier

In issue #779, I'm looking at supporting the Rails error reporter. For
this I want to copy the context (transaction namespace, action name and
tags) from the current transaction when an error is reported by Rails.

This will make determining the namespace and action name for the
transaction easier for Active Job jobs, in the error reporter.

To have the context available to the error handler, it needs to be set
on the transaction before the Active Job job is performed. I have moved
those parts of the instrumentation up to above the `super` call, and not
within the `ensure` block at the very end. The job will already know
what job is run and with what arguments at the start of the
instrumentation.

I can't apply the same improvement for Rails controllers. We only have
the necessary request env values to determine this the controller name
and action after the request has been processed, which is too late for
the error reporter.

.changesets/set-appsignal-transaction-namespace--action-name-and-some-tags-earlier-.md

@@ -0,0 +1,6 @@
+---
+bump: "patch"
+type: "change"
+---
+
+Set the AppSignal transaction namespace, action name and some tags, before Active Job jobs are performed. This allows us to check what the namespace, action name and some tags are during the instrumentation itself.

lib/appsignal/hooks/active_job.rb

@@ -37,12 +37,6 @@ def execute(job)
               )
             end
 
-          super
-        rescue Exception => exception # rubocop:disable Lint/RescueException
-          job_status = :failed
-          transaction.set_error(exception)
-          raise exception
-        ensure
           if transaction
             transaction.params =
               Appsignal::Utils::HashSanitizer.sanitize(
@@ -59,6 +53,15 @@ def execute(job)
             transaction.set_tags(transaction_tags)
 
             transaction.set_action_if_nil(ActiveJobHelpers.action_name(job))
+          end
+
+          super
+        rescue Exception => exception # rubocop:disable Lint/RescueException
+          job_status = :failed
+          transaction.set_error(exception)
+          raise exception
+        ensure
+          if transaction
             enqueued_at = job["enqueued_at"]
             if enqueued_at # Present in Rails 6 and up
               transaction.set_queue_start((Time.parse(enqueued_at).to_f * 1_000).to_i)