Named Import Specifier is missing isTypeOnly in structure

[matt-kinton]

When using ImportSpecifierStructure the structure doesn't contain the isTypeOnlyFlag, this prevents you from creating Type Only Named Imports.

The same issue is also contained in the addImportDeclaration function. You can add Named Imports, but not type only ones.

Version: 16.0.0

To Reproduce

import { Project } from "ts-morph";

const project = new Project();
const sourceFile = project.createSourceFile("test.ts", ``);

sourceFile.addImportDeclaration({
  moduleSpecifier: "test",
  namedImports: [
    {
      // this is missing
      isTypeOnly: true,
      name: "test",
    },
  ],
});

isTypeOnly should be defineable for Named Imports.

Thanks!