Remove unused empty Options structs

[imjasonh]

Lots of packages included empty FooOptions structs which we could use to allow callers to pass optional options to the methods.

In practice, these didn't add anything and just added a wart. Users had to pass foo.FooOptions{}, or &foo.FooOptions{}, or nil to lots of random methods. We weren't consistent about whether options should be accepted as a pointer or not, or whether absence of options should be expressed as a pointer to an empty struct, or nil.

If these methods want to add options in the future, they should do so using functional options, where we can add more options to the method args directly without breaking existing callers.

[codecov-io]

Codecov Report

Merging #278 into master will decrease coverage by 0.01%.
The diff coverage is 77.77%.

@@            Coverage Diff             @@
##           master     #278      +/-   ##
==========================================
- Coverage      55%   54.98%   -0.02%     
==========================================
  Files          58       58              
  Lines        2498     2497       -1     
==========================================
- Hits         1374     1373       -1     
  Misses        907      907              
  Partials      217      217

Impacted Files	Coverage Δ
cmd/ko/resolve.go	0% <0%> (ø)	⬆️
pkg/ko/publish/default.go	70.58% <0%> (ø)	⬆️
cmd/ko/publish.go	9.3% <0%> (ø)	⬆️
pkg/v1/mutate/rebase.go	47.82% <100%> (ø)	⬆️
pkg/v1/daemon/write.go	47.82% <100%> (ø)	⬆️
pkg/v1/remote/write.go	66.04% <100%> (-0.21%)	⬇️
pkg/v1/tarball/write.go	67.12% <100%> (ø)	⬆️
pkg/v1/remote/delete.go	68% <100%> (ø)	⬆️
pkg/ko/publish/daemon.go	60% <66.66%> (ø)	⬆️

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[jonjohnsonjr]

LGTM, want to update all our dependents, too? 😄