Manually exclude line ending changes from diffs

[trichoplax]

It seems Diffy's ignore_crlf option does not work consistently so this removes its use and instead passes normalized before and after strings to Diffy, removing the need for the option.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.02%. Comparing base (def3d07) to head (7498cdb).

Additional details and impacted files

Components	Coverage Δ
controllers	76.84% <ø> (ø)
helpers	85.47% <ø> (ø)
jobs	77.43% <ø> (ø)
models	93.23% <100.00%> (+0.01%)	⬆️
tasks	61.11% <ø> (ø)

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[cellio]

Tested in my dev environment and the diffs are as expected. I tested on old posts, posts created between the normalization fix and develop, and a post newly created while on this branch. Edit diffs and history diffs are aligned and highlight the expected parts, not the entire post. Sometimes when you add a paragraph the previous one is highlighted because of the added newline; it doesn't always happen as shown in this screenshot, but this is existing behavior, not a regression.