spellchecker: include Dutch (nl) dictionary

[TrackPixel]

Adds main_nl.dict to java/res/raw/ to enable Dutch spell checking
and autocorrect suggestions.

Dutch (nl) is already listed in spellchecker.xml but the dictionary
file was missing, so it did not appear under:
Settings → On-screen Keyboard → Text Correction → Add-on Dictionaries

Dictionary source: https://codeberg.org/Helium314/aosp-dictionaries/src/branch/main/dictionaries_experimental
License: CC BY 4.0
Words: 529,699 (updated 2024-07-23)

Note: although this dictionary is listed under "dictionaries_experimental"
in the source repository, the "experimental" label refers to the recency
of the word list — it is built from more recent sources (2024) compared
to the older standard version (2014, 178,444 words). It does not indicate
an unstable or untested dictionary.

[thestinger]

Has this been tested?

[TrackPixel]

Hello @thestinger ,

I have not tested this in a full GrapheneOS build, as I don't have
a build environment available.

However, I'd like to propose testing it via HeliBoard, which is an
AOSP-based keyboard using the exact same .dict format. Would this
be considered a valid way to verify the dictionary works correctly
before merging? Other proposal?

If not, I'm happy to wait for a maintainer or someone with a build
environment to verify it.

[dot166]

@TrackPixel if you want, I could test it, I don't speak Dutch, but I can figure out how to spell a few words to test this

[TrackPixel]

@dot166 I installed the Hellium keyboard, which fixes the issue. The remaining question is whether GrapheneOS should implement dictionary support; that decision rests with @thestinger .
I can provide a list of words and example sentences for testing.