Htmlnano don't remove redundant attributes

[DeMoorJasper]

This will change the defaults of htmlnano to keep default values inside form elements, that could cause css selectors to fail.

Closes #1245

[codecov-io]

Codecov Report

Merging #1249 into master will increase coverage by 1.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1249      +/-   ##
==========================================
+ Coverage   87.38%   88.39%   +1.01%     
==========================================
  Files          77       77              
  Lines        4105     4455     +350     
==========================================
+ Hits         3587     3938     +351     
+ Misses        518      517       -1

Impacted Files	Coverage Δ
src/transforms/htmlnano.js	100% <100%> (+27.77%)	⬆️
src/assets/WebManifestAsset.js	59.18% <0%> (-19.39%)	⬇️
src/assets/JSONAsset.js	84.61% <0%> (-8.72%)	⬇️
src/assets/VueAsset.js	80% <0%> (-7.5%)	⬇️
src/assets/SASSAsset.js	93.61% <0%> (-6.39%)	⬇️
src/assets/TypeScriptAsset.js	97.29% <0%> (-2.71%)	⬇️
src/assets/LESSAsset.js	97.87% <0%> (-2.13%)	⬇️
src/utils/serializeObject.js	88.23% <0%> (-1.77%)	⬇️
src/utils/syncPromise.js	100% <0%> (ø)	⬆️
src/assets/TOMLAsset.js	100% <0%> (ø)	⬆️
... and 23 more

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[devongovett]

hmm we keep finding these unsafe transforms that htmlnano is doing. is there a flag to just turn them all off in one go rather than needing to manually apply each one as we find it?

[DeMoorJasper]

@devongovett Not that I know of, it doesn't mention it in the docs.
I've opened up an issue, with a feature request.