fix @glimmer/core exports for bundlers & node ESM

Previously @glimmer/core build outputs on commonjs
and modules folders were not universally runnable
interchangeably on bundlers are node.js runtimes.
This commit fixes by introducing default export
in addition to named exports.

packages/@glimmer/core/index.ts

@@ -1,13 +1,8 @@
-export {
-  default as renderComponent,
-  RenderComponentOptions,
-  didRender,
-  getTemplateIterator,
-  ComponentDefinition,
-} from './src/render-component';
+import renderComponent, { didRender, getTemplateIterator } from './src/render-component';
 
-export { BaseEnvDelegate } from './src/environment/delegates';
+import { BaseEnvDelegate } from './src/environment/delegates';
 
+export type { ComponentDefinition } from './src/render-component';
 export type {
   ModifierManager,
   ModifierCapabilities,
@@ -16,10 +11,10 @@ export type {
   HelperManager,
 } from '@glimmer/interfaces';
 
-export { templateFactory as createTemplateFactory } from '@glimmer/opcode-compiler';
-export { templateOnlyComponent } from '@glimmer/runtime';
+import { templateFactory as createTemplateFactory } from '@glimmer/opcode-compiler';
+import { templateOnlyComponent } from '@glimmer/runtime';
 
-export {
+import {
   setComponentManager,
   setModifierManager,
   setHelperManager,
@@ -29,6 +24,42 @@ export {
   setComponentTemplate,
 } from '@glimmer/manager';
 
-export { getOwner, setOwner } from '@glimmer/owner';
+import { getOwner, setOwner } from '@glimmer/owner';
+import { precompileTemplate } from './src/template';
 
-export { precompileTemplate } from './src/template';
+export {
+  renderComponent,
+  didRender,
+  getTemplateIterator,
+  BaseEnvDelegate,
+  createTemplateFactory,
+  templateOnlyComponent,
+  setComponentManager,
+  setModifierManager,
+  setHelperManager,
+  componentCapabilities,
+  modifierCapabilities,
+  helperCapabilities,
+  setComponentTemplate,
+  getOwner,
+  setOwner,
+  precompileTemplate,
+};
+export default {
+  renderComponent,
+  didRender,
+  getTemplateIterator,
+  BaseEnvDelegate,
+  createTemplateFactory,
+  templateOnlyComponent,
+  setComponentManager,
+  setModifierManager,
+  setHelperManager,
+  componentCapabilities,
+  modifierCapabilities,
+  helperCapabilities,
+  setComponentTemplate,
+  getOwner,
+  setOwner,
+  precompileTemplate,
+};