fix: Add terser

[shortdiv]

Which problem is this pull request solving?
Addresses the discussion in #73 to minify es bundles.

List other issues or pull requests related to this problem
#76

Checklist

• The status checks are successful (continuous integration). Those can be seen below.

[ehmicky]

Amazing!
🎉

[ehmicky]

I have tried locally.

The integration-test big fixture goes from 556727 to 122,656 bytes (78% reduction).

The config-dir very small fixture goes from 245 to 122 bytes (50% reduction).

Before this PR:

(function(){'use strict';function onRequest() {}var funcc3499c2729730a7f807efb8676a92dcb6f8a3f8f=/*#__PURE__*/Object.freeze({__proto__:null,onRequest: onRequest});netlifyRegistry.set("example", funcc3499c2729730a7f807efb8676a92dcb6f8a3f8f);}());

After this PR:

!function(){"use strict";var e=Object.freeze({__proto__:null,onRequest:function(){}});netlifyRegistry.set("example",e)}();

[ehmicky]

Note: this reduces the func{randomID} to single letter variables. I have been wondering whether this would reverse the benefits of #66 (consistent bundle filenames).

However, this is not the case. The minified bundle content is the same when the source code does not change, and is different when the source code changes. Since the bundle filename is a hash of the bundle content, this should work.

We could optimize though by not generating that random ID anymore though, and only using an incrementing integers, since it does not seem to be useful anymore?

[mraerino]

great!