Add format optional variable to core drivers to support JUNOS get_config() options

[s1mplesimon]

Added format optional variable to core drivers to support JUNOS get_config() text option.

Related to problem #1105

[mirceaulinic]

@s1mplesimon can you apply the following patch to your branch so the tests will pass?

diff --git a/napalm/base/base.py b/napalm/base/base.py
index b1b56040..10448deb 100644
--- a/napalm/base/base.py
+++ b/napalm/base/base.py
@@ -1599,7 +1599,11 @@ class NetworkDriver(object):
         raise NotImplementedError
 
     def get_config(
-        self, retrieve: str = "all", full: bool = False, sanitized: bool = False
+        self,
+        retrieve: str = "all",
+        full: bool = False,
+        sanitized: bool = False,
+        format: str = "text",
     ) -> models.ConfigDict:
         """
         Return the configuration of a device.
@@ -1609,6 +1613,7 @@ class NetworkDriver(object):
                               The rest will be set to "".
             full(bool): Retrieve all the configuration. For instance, on ios, "sh run all".
             sanitized(bool): Remove secret data. Default: ``False``.
+            format(string): The configuration format style to be retrieved.
 
         Returns:
           The object returned is a dictionary with a key for each configuration store:

[s1mplesimon]

@mirceaulinic Applied. Still failing tests, though.

[mirceaulinic]

@s1mplesimon yes, you also need to run black, see https://github.com/napalm-automation/napalm/actions/runs/8572280134/job/23494441598?pr=1972#step:5:12

[mirceaulinic]

Merging and I'll follow up with a PR to fix.