[lit-labs/compiler] Write blog post for this new labs package

[AndrewJakubowicz]

Maybe a title like: "Even Faster Rendering with the new Lit Templates Compiler".

RFC lit/rfcs#21

Blog post should:

• Introduce the compiler
• Talk about the current state and how to use.
• Benchmarks & maybe get some visuals
• Maybe mention that many current benchmarks do not measure the first render (from a fresh page reload).
• Roadmap & future vision
• & CTA for people to try it out.

[AndrewJakubowicz]

Blog post draft at: https://docs.google.com/document/d/1z5DqGtkh5Ky88Dczc3QQh53qxr8EPkdwU7Wujn8d1Wo/edit#heading=h.mqbvi8g6hzd8

[AndrewJakubowicz]

This compiler blog post is now included in the Lit 3.0 release blog post: #1196

Closing, as we'll need to review and address feedback when releasing 3.0.