fix(toast): update toast design to match MD spec

[brandyscarney]

Short description of what this resolves:

Updates the Material Design Toast to closer match the spec: https://material.io/design/components/snackbars.html

Changes proposed in this pull request:

• Updates the animation to use opacity, not translate
• Updates design with the right background, box-shadow, etc.
• Fixes the broken position middle of toast ([v4-beta.15] Toast middle = top #16271) and updates e2e test to include this
• Allows for line breaks to be passed in the message

Ionic Version: 4.x

Fixes: #16271

master	fix-toast-design

[brandyscarney]

Good to merge once checks pass 👍