Jsligo discriminatory union

type:added

Adds support for limited discriminatory unions.

Limitations:

• not supported: a catch-all construct in the switch statement. We always expect all the variants of the type to be used.
• it will not be possible to change a variant after initialization
• it’s always expected that the input of the Switch statement is like this: foo.bar as the last .bar part will be removed.

Changelog details:

JsLIGO: Add support for discriminatory unions.