Added new exception page

[faustinoaq]

Description of the Change

This PR adds a new exception page based on Phoenix one, see: phoenixframework/phoenix#1776

This PR will be required by next amber watch PRs

Alternate Designs

Keep basic error pages

Benefits

• Fixes 400 instead of 500 when params validation failed #770 reported by @c910335
• Add code snippets right in the browser
• Add file navigation
• Add header inspector
• Add Cookies inspector
• Add new awesome design based on Phoenix one with responsive design ✨ Thanks to @rstacruz 🎉

Possible Drawbacks

[x] Reload (watch) checkbox depends on new amber watch configuration (based on amber_reload.js without reload pipe)

[faustinoaq]

Some screenshots 😍

[faustinoaq]

current error page specs by @marksiemers already cover this 👍

[paulcsmith]

@faustinoaq Just finished up extracting this to a shared lib: https://github.com/crystal-loot/exception_page

You should be able to use it here. I removed the "watcher" stuff since it isn't always needed, but you can hook into the provided methods for customizing the buttons and the javascript that are in the README. Feel free to open PRs for stuff you need in case it doesn't cover everything!

[faustinoaq]

@paulcsmith Thanks you so much! Your shard looks very very nice, I gonna use it here now 👍

[eliasjpr]

Lucky already has an exception page base leveraging on this code and Amber yet does not this is a bummer :(

[faustinoaq]

@eliasjpr Yeah. no problem 😅 The new exception_page shard is pretty useful an easy to use, maybe we should close this and open a new PR, WDYT?

[robacarp]

@faustinoaq given the recent migration of a lot of this code to crystal community repo, should this be closed or merged?

[eliasjpr]

@faustinoaq I agree to use the new shard instead you can close this PR and open a new one implementing the shard.