feat(core): Support variadic options

[sidwebworks]

The current parser is a fork of Deno's std/flags parser. However it does not support variadic options out of the box

cli add --files app.js index.html styles.css --no-commit

, hence we need to extend that functionality.

I thought of using yargs-parser due to such reasons but I don't want to introduce any dependencies in the core package

Also from what I understand, yargs-parser seems to use some node specific dependencies which I don't want to add.