Add junos_system declartive module and other related change (#25859)

* Add junos_system declartive module and other related change

*  junos_system declartive module
*  integration test for junos_system
*  integration test for net_system (junos platform)
*  pep8 fixes for junos modules
*  move to lxml from elementree for xml parsing as it support
   complete set of xpath api's
*  other minor changes

* Fix CI and doc changes

* Fix unit test failures

* Fix typo in import

* Fix import issue for py2.6

* Add missed Element in import

lib/ansible/modules/network/junos/junos_package.py

@@ -79,6 +79,7 @@ options:
     choices: ['true', 'false']
 requirements:
   - junos-eznc
+  - ncclient (>=v0.5.2)
 notes:
   - This module requires the netconf system service be enabled on
     the remote device being managed
@@ -142,7 +143,8 @@ def install_package(module, device):
     package = module.params['src']
     no_copy = module.params['no_copy']
 
-    progress_log = lambda x, y: module.log(y)
+    def progress_log(dev, report):
+        module.log(report)
 
     module.log('installing package')
     result = junos.install(package, progress=progress_log, no_copy=no_copy)