Support serverless deployment

[sidealice]

I try to deploy LTS in a serverless environment. But have a problem that "aydin-hassan/magento-core-composer-installer" required Composer and it's mapping logic to the files.

I can modify the root dir to other path and avoid to use composer update command to deployment.
But the problem is I can't get the benefits from composer for the update with LTS .

    "extra": {
        "magento-core-package-type": "magento-source",
        "magento-root-dir": "htdocs/"
    },

If in the future we can replace all core modules with different independent repo. And this would be helpful for the improvement for each modules.

Because most of the core modules are not production ready with features but could be a good base for the customization. If sepreate into modules and standalone repo, LTS can enjoy the unit test and integration test from that.

In the future, a headless ecommerce would be the in common. And serverless platform with a modular formed sub system, each module may communicated with event/message queue via bus. Thus LTS sepreate the system into modular parts would let the old system new birth. It would make new possible for the magento LTS embrace with serverless