Add hot reloading to arrower cli

[HTechHQ]

As a developer, I want to have hot reloading of my project so I see changes to my website immediately with the convenience other ecosystems (js) are offering.

• Life reload on Go code changes
  • for *.go files
  • for *.config and *.yaml files
  • not for view templates and test files, as views can be reloaded without a new build and application start and test files don't change app behaviour
• Hot reload the browser tab on life reload and HTML template changes automatically
  • for changes on the view templates only, the whole app does not have to be restarted to minimise delay and resource usage
  • the reload needs to consider a possible startup time of the app, especially if it is an enterprise app connecting to many services it's probably not ready as soon as the build step is finished
• Print lovely log messages in stdout, that make it clear in which step Arrower is running as well as what are application logs
• Log output
  • Arrower version
  • Which directory is watched
  • "building..." in orange
  • "warnings/error in red"
  • "running..." in yellow
  • original app logs
  • " has changed" (relativ path) in purple

[HTechHQ]

When running the app:

• [x] on first run start browser and open web app URL
• [x] otherwise signal browser a hot reload

[HTechHQ]

• [x] Add test case to BuildAndRunApp: a program that ignores sigterm
• [x] Debounce of change events
• [x] On sigterm of arrower run => signal and stop the app first, before terminating arrower

[HTechHQ]

• [x] Output from log.Println is not showing when the developer's app is started with arrower run
• [x] if compilation fails, because of an syntax error it shows build & run failed: could not build app binary: <nil> => can it show a more detailed and helpful compiler message, with the file and line number of what is wrong?

[HTechHQ]

Hot reload is working smoothly so far. Bugs and improvements will go into their own issues.

Some closing thoughts, for future reference:

• What about JS files? Do they require a full page reload, or can some trickery like the CSS loading be used?
• What about images and other frontend assets?
• Does it work only with files from disc or also with go embedding?
• Does the MW handle HTMX.org requests?
• Ensure HTTP cache is configured properly to not interfere with hot reloading

[HTechHQ]

Possibly the life reload needs to take care of the following steps as well:

• go generate
• go mod tidy