record: don't honor format-changing diffopts (issue4459) record does support the whitespace options, so honor those. In upcoming patches we'll replace all the other uses.

patch.difffeatureopts: add a feature for format-changing diffopts Typically, callers that are interested in this set are also interested in the others. We still add it as a first-class flag for convenience.

patch.difffeatureopts: add a feature for whitespace diffopts These aren't exactly format-breaking features -- just ones for which patches applied to a repo will produce incorrect commits, In any case, some commands like record and annotate only care about this feature.

patch.difffeatureopts: add a feature for diff.git This deserves to be its own feature -- indeed, this is often the only feature several commands care about.