Improve scaffold views

[patriciomacadden]

I made a few modifications to the scaffold views. I'm attaching some images to showcase the before/after of these changes. The changes:

• remove the mx-auto to most of the views. It makes the scaffold weird as you have to re-focus your sight on every new page. Keep the w-2/3 so the content always starts in the same place.
• add titles to all pages (show page never had a title IIRC). I think this is nice to keep consistency.
• add content_for :title to all pages as it was only present in the index view
• add a hover state to buttons and links and adjust the padding
• add semantic colors to buttons (just the destroy one, made it red).
• add an empty state when the list has no items
• change the border/focus colors on errored fields
• improve the errors list
• fixed minor indentations and removed some empty spaces on generated views

I think these are nice changes/additions. Let me know if you agree. I intend to keep contributing these kind of changes if it's something people like.

Before and after pictures:

before	after

button states:

normal	hover

[flavorjones]

I love it, this is a big improvement.

If you want to continue contributing scaffold improvements, it would be very welcome!

[flavorjones]

Shipped in https://github.com/rails/tailwindcss-rails/releases/tag/v3.2.0

[patriciomacadden]

thanks @flavorjones! Definitively will be contributing more stuff!