Unroll shader loop when running on Windows to avoid shader crashes

[daniel-wer]

Review hiding whitespace changes!

I added that both the fragment and the vertex shaders are unit-tested.

URL of deployed dev instance (used for testing):

• https://usedifferentshaderforwindows.webknossos.xyz

Steps to test:

• Enable interpolation and open a couple of dataset on Windows

TODOs:

• [ ] ...

Issues:

• fixes #

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(Please delete unneeded items, merge only when none are left open)

• [x] Added changelog entry (create a $PR_NUMBER.md file in unreleased_changes or use ./tools/create-changelog-entry.py)
• [ ] Added migration guide entry if applicable (edit the same file as for the changelog)
• [ ] Updated documentation if applicable
• [ ] Adapted wk-libs python client if relevant API parts change
• [x] Removed dev-only changes like prints and application.conf edits
• [x] Considered common edge cases
• [ ] Needs datastore update after deployment