Break Electrobun's CLI into separate (cli and dev launcher) binaries.

[YoavCodes]

Currently the Electrobun CLI is a single-file-executable bun app. It has two main functions that should be broken up into two separate binaries

1. CLI

This is used for reading electrobun.config file, building application bundles, running BSDIFF for generating tiny update patches and so on. Consider rewriting this in zig to make the electrobun npm distributables much smaller.

2. Dev Launcher

For dev builds the current cli is just placed into the application bundle as the launcher. It was just easier to get all the stdio forwarding working in the prototype this way. There already exists a separate zig launcher for production builds. That should be expanded or a dedicated zig dev launcher should be created.

Should probably do this before adding windows/linux support

[YoavCodes]

Might defer this till later since it's not blocking cross platform support