Requested feature: Applying subschemas conditionally

[JonasHorvli]

Prerequisites

• [ x] I have read the documentation;
• [ x] In the case of a bug report, I understand that providing a SSCCE example is tremendously useful to the maintainers.
• [ x] Ideally, I'm providing a sample JSFiddle or a shared playground link demonstrating the issue.

Description

First of all: thanks for this lib, it has made making forms so much easier and are currently using this in our application as better option then a simple code editor.

Draft 7 allows "if", "then" and "else" keywords, but it does not seem to be supported in the form.
We would like certain properties to have a different pattern or only be shown depending on the certain value of the first property. An example would be a postal code is different depending on the country you choose.

Documenation on JSON schema conditionals:
https://json-schema.org/understanding-json-schema/reference/conditionals.html

rfjs example in demo (Postal code is missing in form):
https://rjsf-team.github.io/react-jsonschema-form/#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

Thank you in advance!
Jonas

[epicfaace]

Good suggestion -- that would be a useful feature. This is a duplicate of #885.