feat: prebundle code + restore from snapshot

[marvinhagemeister]

This PR allows you to prebundle all islands and other code needed for the browser ahead of time. The workflow with this is that you have a GitHub action where you build the assets and then deploy from there.

Pros:

• Files are served as quick as deploy + fresh can serve them
• No need to fetch dependencies when an isolate spins up
• Makes deployments reproducible since they cannot be affected by outages from third parties like esm.sh anymore
• The bigger the island code the more noticeable the speed improvement

Cons:

• Makes deployments 10-15s longer
• Requires GH Actions to be set up

Assets can be generated by running deno task build and the main.ts script will pick up the snapshots automatically if one is there. When it does it prints a message to the terminal.

The speed difference is best shown with a video. In the ahead of time (AOT) bundled version the agolia search loads nearly instantaneously. Go to https://fresh-www-test.deno.dev/ to see that for yourself.

output.mp4

The main difference to #1450 is, that this accounts for plugins and includes a way to generate the bundles + snapshots directly in Fresh.

Fixes #1062

[lino-levan]

This is a very similar approach to what I did in #1084 for a PoC. I think this is the right way to do it. +1 for the concept.

[marvinhagemeister]

Gonna do the documentation update in another PR since the deploy page needs an overall in general.

[fdemir]

We should add this to the documentation.

[bartlomieju]

LGTM 🚀

[marvinhagemeister]

Added a page to our documentation and I think the PR is ready to be merged.

[lino-levan]

Let me take a look!

[lino-levan]

Nice! Excited to have this land.