TSX/JSX vs Tagged Template Literals

After reading about [TSX/JSX on the official TypeScript website](https://www.typescriptlang.org/docs/handbook/jsx.html), and a long conversation on the DFF discord channel, I'm now convinced that TSX/JSX (I'll call it XSX from now on) is a better option than [tagged template literals](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals) (which I'll call TTL) for a templating mechanism. Here's why:

1. **De Facto Standard**: TSX is as much of a standard as TS at this point. Deno supports both of these "standards". @timreichen was championing TTLs because of their support in the web platform. In my opinion, Deno extends the web platform to include TS(X), so, because this is a Deno-first framework, and Deno supports these "secondary standards", we should be treating them as part of the "augmented-js-standards"-based platform.
2. **Type Checking Supported Out-of-the-box**: Deno already type checks XSX, so doesn't need a custom TTL parser to be able to type check elements/attributes/children.
3. **Parsing the Template Occurs Ahead-of-time**: Parsing the template into function calls occurs AOT in XSX and occurs at runtime using native TTL. This runtime parsing incurs a performance cost.

The issue names no files, tests, or entry points. Start by locating the current templating implementation and comparing its tagged-template approach with the proposed TSX/JSX approach; done would require an agreed direction and a defined migration scope.

Written by the indexing model from the issue text.