Json module extraction

[Jolanrensen]

Fixes #100

• Extracts JSON reading/writing to dataframe-json
• Internal calls to :core are done via a friend module setup, like with dataframe-jupyter. Hopefully this can be simplified when the IDE gets full friend-module support
• The dataframe package includes dataframe-json by default, as expected
• dataframe-csv, and dataframe-excel allow writing DataFrame/DataRow as json. I rewrote this via a reflection call for now, prompting the user to add the dataframe-json package if they need this functionality. This is a bit hacky and might need a better solution. I was thinking of adding a toStr function in the SupportedDataFrameFormat service. That way they can check supportedFormats for a SupportedDataFrameFormat that accepts the json extension and call that generic one.
• dataframe-csv, and dataframe-excel depend on dataframe-json by default, but this dependency can be manually and safely excluded when working only with flat data.
• reading (nested) json is done via parsing. This might need a similar solution. Either by using SupportedDataFrameFormat for parsing String -> AnyRow/AnyFrame or by allowing the parser to become pluggable itself (Allow custom Parsers #962). Solved with reflection for now

[Jolanrensen]

@koperagen @zaleslaw @AndrewKis As discovered by @ileasile we'd better migrate all jupyter dependencies to gradle.build.kts instead of the jupyter integration. We can see that readJsonStr now breaks for notebooks.

[Jolanrensen]

@ileasile Thanks ❤️