* junos_linkagg implementation and junos modules refactor
* junos_linkagg implementation
* junos_linkagg integration test
* net_linkagg integration test for junos
* decouple `load_config` and `commit` operations,
to allow single commit (in case on confirm commit) and
to perform batch commit (multiple `load_config` followed by single
`commit`)
* Other related refactor
* Fix CI issues
* Fix unit test failure
