New module: access Cisco ACI (network/aci/aci_rest) (#26029)

* aci_rest: New module to access Cisco ACI

This PR includes:
- Relicense as GPLv3+
- Check-mode support
- Cosmetic changes to documentation
- Examples in YAML format
- Removal of incorrect requirements (for this module)
- Do not log passwords
- Implement native fetch_url instead of requests
- Use standard hostname, username and password parameters
- Add alias src for parameter config_file
- Add mutual exclusive content option for inline data (and show some inline examples)
- Add timeout parameter
- Add validate_certs parameter
- Handling ACI result output (identical for JSON as XML input)
- Parse/expose ACI error output to user

* Lower case method, add use_ssl, Use python dicts

This commit includes:
- Use lowercase method names
- Add `use_ssl` parameter (not the `protocol` parameter)
- Use a python dict for the request data (not a JSON string)
- Documentation improvements

* Ensure one of 'content' or 'src' is provided

* Fix issue with totalCount being a string in JSON

This fixes the problem with JSON output where totalCount is a string and
not an integer.

This fixes jedelman8/aci-ansible#7

* Improve code documentation

* Improve error handling and module response

* Small typo

* Improve documentation and examples

* Keep protocol parameter, but deprecate it

* Extrude aci functions from module_utils

* aci_rest: Add unit tests

test/runner/requirements/units.txt

@@ -25,3 +25,6 @@ deepdiff
 
 # requirement for modules using Netconf protocol
 ncclient
+
+# requirement for aci_rest module
+xmljson