Change the expected exported name of plugin declarations to be "plugin"
at the main entrypoint instead of the default export. This makes the
plugin's code organisation more flexible especially when using CommonJS
JavaScript modules as they can export additional symbols from the
plugin declaration file.
Refactor away the config group concept and simplyfy the way config
fields are defined. Fields are defined directly as properties of the
static field fieldDefinitions on the class itself with a separate
interface to declare the types of fields.
This makes it possible to easily make accessing the config fields type
checked in a way that lets plugins extend the interfaces with their own
config options by adding additional fields to the interface via
declation merging.
Hornwitser