Schemapicker: Elements attributes definition

[JakobVogelsang]

As a user of open-scd-core I want to have an algorithm that returns the definition attributes for a given SCL element including its restriction defined by a given SCL schema.

Background
When receiving a wizard event for an element that is not added to the wizard library, we need to have a fallback mode wizard. Such a wizard is constructed of inputs for each of the attitudes of the element. Each of the attributes can have restriction defined in the schema that shall be added of the inputs in the wizard.

Requirements

• return an object for each attribute of a given SCL element, including its restrictions based on a given schema

Proposed interfaces

function getAttributes(tagName: string, schema:XMLDocument): Record<string, Attribute>

interface Attribute {
  base: string;
  namespaceURI?: string;
  value?: string | null;
  defaultValue?: string;
  enumeration?: string[];
  required?: boolean;
  pattern?: string;
  maxLength?:string;
  minLength?: string;
}