Integrate crate-metadata fork

[facboy]

Are there any plans to integrate the changes in https://github.com/crate-metadata/json-patch?

[huggsboson]

I merged the json-schema ones. Happy to merge a PR that copies them over.

[huggsboson]

The only wrinkle is I'm not sure if we diverged from the spec at all with those patches.

[facboy]

hmm...how can you tell?

[huggsboson]

I probably just have to look through. Was there any particular patchset you wanted pulled forward?

[facboy]

hmm...at the moment we are dependent on some of the introduced operations, though whether we actually use them in practice, i'm not sure.

[facboy]

after some tidy up i think we can return to using this library without the crate-metadata changes - now that this is being maintained i suspect it's better to stay closer to the RFC standard without the extra operations. were there any bug-fixes or improvements on the fork that aren't related to the extra operations?