Zabbix

...G...... [ZBX-26755] fixed problem with mqtt plugin in agent 2 not establishing connection if first call failed

* commit 'ef4e59d25c454081df8ae6a42e3b13f4835e4794':
  ...G...... [ZBX-26755] improved changelog
  ...G...... [ZBX-26755] fixed several topics ruining the connection
  ...G...... [ZBX-26755] added changelog
  ...G...... [ZBX-26755] updated sdk to master branch version
  ...G...... [ZBX-26755] improved async logic and made it safer from any async interaction from outside.
  ...G...... [ZBX-26755] improved concurrency resistance
  ...G...... [ZBX-26755] golangci.yaml adjustments. Added errs.WrapConst(
  ...G...... [ZBX-26755] code style improvements
  ...G...... [ZBX-26755] improved proof of work version of connection establishing backoff
  ...G...... [ZBX-26755] basic working example with increasing backoff, that might have concurrency issues.
  ...G...... [ZBX-26755] updated code style mainly by linter suggestions