Update flows to use event.dataset (#10063)

* Update flows to use event.dataset

event.type is a reserved field for ECS and event.dataset is a more appropriate field for this
identifying the what produced the event. And we'll keep type until we are done updating
Packetbeat for ECS, at which time we can reevaluate if we want to change anything w.r.t.
the common fields used in several Packetbeat datasets (like path, query, type, status).

* Update Packetbeat Flows dashboard

CHANGELOG.next.asciidoc

@@ -143,6 +143,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 *Packetbeat*
 
 - Add `network.community_id` to Packetbeat flow events. {pull}10061[10061]
+- Add aliases for flow fields that were renamed. {issue}7968[7968] {pull}10063[10063]
 
 *Functionbeat*
 

dev-tools/ecs-migration.yml

@@ -835,6 +835,40 @@
   alias: false
   comment: Don't add an alias until all of Packetbeat stops using this field.
 
+## Flows
+- from: flow_id
+  to: flow.id
+  alias: true
+
+- from: final
+  to: flow.final
+  alias: true
+
+- from: start_time
+  to: event.start
+  alias: true
+
+- from: last_time
+  to: event.end
+  alias: true
+
+- from: source.stats.net_bytes_total
+  to: source.bytes
+  alias: true
+
+- from: source.stats.net_packets_total
+  to: source.packets
+  alias: true
+
+- from: dest.stats.net_bytes_total
+  to: destination.bytes
+  alias: true
+
+- from: dest.stats.net_packets_total
+  to: destination.packets
+  alias: true
+
+
 # Heartbeat
 
 - from: monitor.scheme

packetbeat/_meta/fields.common.yml

@@ -89,6 +89,41 @@
         this field will be an array with the outer tag's VLAN identifier listed
         first.
 
+    - name: flow_id
+      type: alias
+      path: flow.id
+      migration: true
+
+    - name: final
+      type: alias
+      path: flow.final
+      migration: true
+
+    - name: vlan
+      type: alias
+      path: flow.vlan
+      migration: true
+
+    - name: source.stats.net_bytes_total
+      type: alias
+      path: source.bytes
+      migration: true
+
+    - name: source.stats.net_packets_total
+      type: alias
+      path: source.packets
+      migration: true
+
+    - name: dest.stats.net_bytes_total
+      type: alias
+      path: destination.bytes
+      migration: true
+
+    - name: dest.stats.net_packets_total
+      type: alias
+      path: destination.packets
+      migration: true
+
 - key: trans_event
   title: "Transaction Event"
   description: >