Deduplicate serve code with hot reloading in the CLI crate

[ealmloff]

Combines some code in the CLI that serves the hot reload and non-hot reload version of the cli.

This fixes some issues that were applied to only the non-hot-reloading version of the code. Fixes #1041.

This will also fix hot rsx reloading after any changes that require a full rebuild happens. For example after this change:

p { "{10 * 10}" }
->
p { "{10 * 20}" }

The page reloads but this change currently fails to hot reload:

p { "{10 * 20}" }
->
p { "{10 * 20}" }
"This should be hot reloadable"

This PR makes the second change hot reloadable.

[jkelleyrtp]

Perfect - I think this was the issue I was seeing with hotreloading before!