refactors nxos module to use persistent connections (ansible#21470)

This completes the refactor of the nxos modules to use the persistent
connection.  It also updates all of the nxos modules to use the
new connection module and preserves use of nxapi as well.

lib/ansible/module_utils/netcfg.py

@@ -28,6 +28,7 @@
 import re
 
 from ansible.module_utils.six.moves import zip
+from ansible.module_utils.network_common import to_list
 
 DEFAULT_COMMENT_TOKENS = ['#', '!', '/*', '*/']
 
@@ -361,3 +362,91 @@ def add(self, lines, parents=None):
                     self.items.append(item)
 
 
+class CustomNetworkConfig(NetworkConfig):
+
+    def expand_section(self, configobj, S=None):
+        if S is None:
+            S = list()
+        S.append(configobj)
+        for child in configobj.children:
+            if child in S:
+                continue
+            self.expand_section(child, S)
+        return S
+
+    def get_object(self, path):
+        for item in self.items:
+            if item.text == path[-1]:
+                parents = [p.text for p in item.parents]
+                if parents == path[:-1]:
+                    return item
+
+    def to_block(self, section):
+        return '\n'.join([item.raw for item in section])
+
+    def get_section(self, path):
+        try:
+            section = self.get_section_objects(path)
+            return self.to_block(section)
+        except ValueError:
+            return list()
+
+    def get_section_objects(self, path):
+        if not isinstance(path, list):
+            path = [path]
+        obj = self.get_object(path)
+        if not obj:
+            raise ValueError('path does not exist in config')
+        return self.expand_section(obj)
+
+
+    def add(self, lines, parents=None):
+        """Adds one or lines of configuration
+        """
+
+        ancestors = list()
+        offset = 0
+        obj = None
+
+        ## global config command
+        if not parents:
+            for line in to_list(lines):
+                item = ConfigLine(line)
+                item.raw = line
+                if item not in self.items:
+                    self.items.append(item)
+
+        else:
+            for index, p in enumerate(parents):
+                try:
+                    i = index + 1
+                    obj = self.get_section_objects(parents[:i])[0]
+                    ancestors.append(obj)
+
+                except ValueError:
+                    # add parent to config
+                    offset = index * self.indent
+                    obj = ConfigLine(p)
+                    obj.raw = p.rjust(len(p) + offset)
+                    if ancestors:
+                        obj.parents = list(ancestors)
+                        ancestors[-1].children.append(obj)
+                    self.items.append(obj)
+                    ancestors.append(obj)
+
+            # add child objects
+            for line in to_list(lines):
+                # check if child already exists
+                for child in ancestors[-1].children:
+                    if child.text == line:
+                        break
+                else:
+                    offset = len(parents) * self.indent
+                    item = ConfigLine(line)
+                    item.raw = line.rjust(len(line) + offset)
+                    item.parents = ancestors
+                    ancestors[-1].children.append(item)
+                    self.items.append(item)
+
+
+