Support readOnly property from latest validation draft

[norpan]

Reasons for making this change

Since the readOnly property now is available in the latest validation draft (previously it was in hyper schema only), it makes sense to use this property to signal read only for fields.

Fixes #976

Checklist

• I'm updating documentation
  • I've checked the rendering of the Markdown text I've added
  • If I'm adding a new section, I've updated the Table of Content
• I'm adding or updating code
  • I've added and/or updated tests
  • I've updated docs if needed
  • I've run npm run cs-format on my branch to conform my code to prettier coding style
• I'm adding a new feature
  • I've updated the playground with an example use of the feature

[epicfaace]

Thanks for the PR, @norpan , can you please update the documentation in your PR as well?

@handrews , I have a question, how does the json schema draft process work -- is draft-07 finalized and won't change? Since readOnly is only in the the latest version of draft-07, I'm wondering if there's a chance that readOnly will be removed by the time draft-07 is finalized. (This is because in the past, react-jsonschema-form implemented enumNames but that move ended up being too early as enumNames was never actually finalized in jsonschema.)

[handrews]

@epicfaace draft-07 is published and will not change. While technically there were two sets of IETF documents referred to as "draft-07" (draft-handrews-json-schema*-00 and draft-handrews-json-schema*-01) there were no differences in implementation requirements. Which is why we kept "draft-07" for both- the -01 documents were just bugfixes and clarifications.

The whole thing where meta-schemas are called "draft-NN" and IETF documents are "draft-author-topic-NN" where the two values of NN don't match is way too confusing, so we will be moving to date-based meta-schema identifiers for the next draft. So instead of "draft-08", draft-handrews-json-schema*-02 will correspond to "draft/2019-02" or something like that.

[epicfaace]

@norpan will you be able to update the doc? Once you do that, I can merge this PR.

[epicfaace]

@norpan , just bumping this -- will you be able to update the docs?

[pahen]

I would love to see this merged very soon since I'm desperately in need of it.

[pahen]

I've rebased @norpan changes against the master branch and fixed one failing test and updated docs in this PR now: #1282

[epicfaace]

Suggested change

	props.readonly || uiSchema["ui:readonly"] || schema["readOnly"]
	props.readonly || uiSchema["ui:readonly"] || props.schema.readOnly || schema.readOnly

To be consistent with the changes done in 497620f

[pahen]

This can be closed now @epicfaace

[epicfaace]

Yes. Closing because of PR #1282