feat: ✨ Config JSON: Only log notice for no custom JSON once

[ithinkandicode]

When the config JSON code wants to log that it's tried to find a custom JSON file but couldn't find one, it will not only log a notice to say this once.

Also adds a new array variable to mod_loader called logged_messages. Config JSON's missing JSON messages are pushed to this array, which lets us check to see if the exact message was already logged.

Closes #133:

• Config JSON: Limit logging when there's no custom JSON file #133

[Qubus0]

for performance, it could be worth to store all the messages in a dictionary with the keys being their md5 version.
A it doesn't have to look for the entire message every time
B dictionary lookup is way faster
C we can still get all the messages by just using .values()

    print("Config JSON Notice: something something".md5_text())     # b1f526f21bb565e91f11096f3cc1b499
    print("Config JSON Notice: something something".md5_text())     # b1f526f21bb565e91f11096f3cc1b499 - same
    print("abc Config JSON Notice: something something".md5_text()) # 34b0bb58ba94c388f7dd361ec0836172 - not same

[ithinkandicode]

@Qubus0 That's a good idea but I think it might be better to suggest that on issue #140?

• Logging: Track logged messages #140

When 140 is implemented, the code here will change anyway

[Qubus0]

Then let's fast forward to #140