Better support for global registration patterns

## Suggestion It seems likely the compiler logic used for globalThis could be reused to support automated global types for custom elements , which is especially annoying and difficult to deal with in jsx ## Use Cases this is the current dev workflow for creating and using custom elements The custom element loading-spinner.ts ```ts class LoadingSpinner extends HTMLElement { constructor() { super(); this.innerHTML = `<div class="loading-spinnner">` } //omitting code for brevity } customElements.define('loading-spinner', LoadingSpinner); //<-- could this be added to a global namespace using similar logic as globalThis ? ``` the type definition loading-spinner.d.ts ```ts //this is coupled to a specific JSX namespace's types (preact in this case) //maybe adding a JSX.CustomElementsNamespace to lib.d.ts could be an option as well? interface LoadingSpinner extends JSX.HTMLAttributes {} declare namespace JSX { interface IntrinsicElements { 'loading-spinner': LoadingSpinner; } } ``` Using the custom component usage in a jsx component ```ts import h from Reactish let MyComponent = () => { return ( <loading-spinner/> //<--so difficult not to get errors here ) }