Accumulated changes for message queue (#6600)

* rename

* set agent address

* refactor

* add agent sub

* pub messages

* grpc new client

* can publish records via agent

* send init message with session id

* fmt

* check cancelled request while waiting

* use sessionId

* handle possible nil stream

* subscriber process messages

* separate debug port

* use atomic int64

* less logs

* minor

* skip io.EOF

* rename

* remove unused

* use saved offsets

* do not reuse session, since always session id is new after restart

remove last active ts from SessionEntry

* simplify printing

* purge unused

* just proxy the subscription, skipping the session step

* adjust offset types

* subscribe offset type and possible value

* start after the known tsns

* avoid wrongly set startPosition

* move

* remove

* refactor

* typo

* fix

* fix changed path

weed/Makefile

@@ -41,6 +41,10 @@ debug_mq:
 	go build -gcflags="all=-N -l"
 	dlv --listen=:2345 --headless=true --api-version=2 --accept-multiclient exec ./weed -- -v=4 mq.broker
 
+debug_mq_agent:
+	go build -gcflags="all=-N -l"
+	dlv --listen=:2346 --headless=true --api-version=2 --accept-multiclient exec ./weed -- -v=4 mq.agent -broker=localhost:17777
+
 debug_filer_copy:
 	go build -gcflags="all=-N -l"
 	dlv --listen=:2345 --headless=true --api-version=2 --accept-multiclient exec ./weed -- -v=4 filer.backup -filer=localhost:8888 -filerProxy -timeAgo=10h