Fix formatting of code longer than Discord's message limit

[Neil-Tomar]

Description of the Changes

The "Format Code" / "Format and Indent Code" message commands and the /format-code slash command failed when the target message was longer than Discord's 2000-character limit: the whole snippet was wrapped in a single code block and sent as one message, which Discord rejects — so the command silently did nothing.

This PR splits the formatted output into chunks that each stay under the limit:

• New Code class splits content into ≤1980-character chunks (breaking on newlines where possible) and renders each as a code block.
• The commands acknowledge the interaction by replying with the full, unsplit code as an attached file, then post the chunks in order.
• New Language enum + Language.fromString(...) maps the slash command's format option to a code-fence tag.

A follow-up PR will add the language-selection dropdown.

[danthe1st]

Congratulations on writing your first pull request. I commented on a few things I noticed. Please don't unnecessarily duplicate code.

[danthe1st]

Fixes #537

[danthe1st]

These are mostly minor comments. Is there any good reason why users would want a file response in addition to the codeblocks?

[danthe1st]

Overall, your PR looks pretty good.

During testing, I noticed that it's possible to send a single message that can result in a lot of individual (and big). As an example, you can generate the content of such a message with the following code:

System.out.println("{".repeat(30)+"\n"+"a\n".repeat(1000)+"}".repeat(30));

Please add a limit to this. I don't want to have to clean that up without knowing the exact number (I think it is possible to trigger more than 500 messages with a single message that way). See the second review comment here for how to fix it.

[danthe1st]

There's one small typo remaining, otherwise it looks good.

[danthe1st]

Looks good, I added some minor changes after testing.