Add AttrDict to JSON module for use with object_hook

AttrDict is used improve the readability of nested data access from JSON files. Compare:

 config.servers.setup.interfaces.mgmt.protocol
 config["servers"]["setup"]["interfaces"]["mgmt"]["protocol"]

Victor's research showed that tooling this is very popular in Python world and the implementation dates back quite far. At first I suggested I suggested extending SimpleNamespace(); instead, Guido recommended putting this is the JSON module which is where it would primarily be used:

with open('kepler.json') as f:
    kepler = json.load(f, object_hook=AttrDict)
print(kepler.orbital_period.neptune)

Linked PRs

• Revert "GH-96145: Add AttrDict to JSON module for use with object_hook (#96146)" #105948
• [3.12] Revert "GH-96145: Add AttrDict to JSON module for use with object_hook (GH-96146)" (GH-105948) #106117
• gh-96145: Add AttrDict to JSON module for use with object_hook #96146

Done

Done