feat: add NFKC normalization to autocomplete

[Asraye]

Adds NFKC normalization to autocomplete, so things such as "𝑨𝒔𝒓𝒂𝒚𝒆" will show up in user mentions, or "𝑪𝒉𝒆𝒆𝒔𝒆" in channel/role mentions.

We only have to normalize the label, we keep display label as the formatted text as It gives a better user-feedback.

What Is NFKC?

Thought I'd add this section, as a lot of people don't know the beautiful thing of NFKC!

NFKC stands for "Normalization Form Compatibility Composition". It's an unicode normalization form that converts text into a standardized representation by applying compatibility mappings and then recomposing characters where possible :P

This is good as it means that many accented or otherwise stylized unicode characters are converted into more standard equivalents, for example: 𝑪𝒉𝒆𝒆𝒔𝒆 becomes Cheese and ① becomes 1

We can use NFKC here as it helps autocomplete work more consistently with accented or stylized text. Compared to NFC (Normalization Form Canonical Composition), NFKC is more aggressive and normalizes a wider range of visually similar characters, which is better suited for this usage.

How was this PR tested?

Tested locally with all autocompletes.

Screenshots & Screencasts (if appropriate)

Checklist:

• I have carefully read the contributing guidelines
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation if applicable
• I have no unrelated changes in the PR
• I have confirmed that any new dependencies are strictly necessary
• I have written tests for new code (if applicable)
• I have followed naming conventions/patterns in the surrounding code

Please declare, if any, LLM usage involved in creating this PR

None
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[Pecacheu]

Working for me! Glad someone knows what this NFKC thing even is cause I had no idea it had an acronym I just call it "fancy emoji letters" lol