Update pgSQL protocol to use ECS fields

That dashboard was updated too.

Here's a summary of what fields changed.

Part of elastic#7968

Changed

- bytes_in -> source.bytes
- bytes_out -> destination.bytes
- notes -> error.message
- responsetime -> event.duration (unit are now nanoseconds)

Added

- destination
- event.dataset = pgsql
- event.end
- event.start
- network.bytes
- network.community_id
- network.protocol = pgsql
- network.transport = tcp
- network.type
- source

Removed

- pgsql.iserror - It was a boolean that reflected the same information as `status` which uses OK or Error.
- pgsql.query - It was in fields.yml but not in the code.

Unchanged Packetbeat Fields

- method
- query
- status
- type = pgsql (we might remove this since we have event.dataset)

CHANGELOG.next.asciidoc

@@ -80,6 +80,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Changed DHCPv4 protocol fields to align with ECS. {pull}10089[10089]
 - Changed AMQP protocol fields to align with ECS. {pull}10090[10090]
 - Changed Redis protocol fields to align with ECS. {pull}10126[10126]
+- Changed pgsql protocol fields to align with ECS. {pull}NNNNN[NNNNN]
 - Changed HTTP protocol fields to align with ECS. {pull}9976[9976]
 - Changed MongoDB protocol fields to align with ECS. {pull}10158[10158]
 - Changed MySQL protocol fields to align with ECS. {pull}10155[10155]