Initial implementation of Data Links

[radeusgd]

• [ ] Introduce a datalink format that is detected based on extension .datalink
  • It is parsed as JSON.
  • [ ] Extend the dataLinkSchema.json with a version number.
    • [ ] We are also considering to extend it with the library name (e.g. Standard.AWS). This way if the library import is missing and the format is not recognized, we can give the user a clearer error and even provide auto-fixes in the future.
  • [ ] Parser should check the version number and reject datalinks created with newer Enso version as they may contain unsupported parameters.
• [ ] Introduce a DataLinkSPI (or similar) that allows to register new types of datalinks by external libraries.
  • If a datalink type is unrecognized, report an error that the user should import a library.
  • TODO: should we tell which lib so that we could automate the import in the future?
• Implement datalinks that allow to read:
  • [ ] an S3_File
    • [ ] it should allow setting the AWS credentials and allow the keys to contain Enso_Secret
    • [ ] it should read the underlying file and parse it using the default format
  • [ ] a HTTP request