gitbook dev for CLI (#131)

* update package-lock

* use node 18.15

* install miniflare in @gitbook/cli as dev dep

* integrations dev server

* dev tunnels using cloudflared

* refactor with spinners

* add comment

* add more comments

* fix lint

* external fsevents

* build in tmp dirs

* use random available port

* change dev config file name

* cleanup on SIGINT

* update messaging after server started

* add mode in build for minify/sourcemap

* remove port option

* gitignore rollback

* remove extra line in gitignore

* remove port const export

* fix text

* fix error log

* global variable MODE for the runtime

* space as an arg

* comment

* define vars in esbuild

.nvmrc

@@ -1 +1 @@
-18.4.0
+18.15.0