File Input: New Pattern

[ianmcburnie]

We need to create a new pattern for file input (a custom view/facade for input type=file). We'll need to try and stay as generic as possible, given there are numerous customizations of this out in the wild.

[cordeliadillon]

Documented in MIND documentation:

• File Input pattern: https://ebay.gitbook.io/mindpatterns/input/file-input
• Related file preview card pattern: https://ebay.gitbook.io/mindpatterns/messaging/file-preview-card

Do we also want coded examples?