Addition of form fields components to Venia PWA [WIP]

[ericerway]

This issue is for the following packages:

[X] venia-concept
[ ] pwa-buildpack
[ ] peregrine
[ ] pwa-module
[ ] pwa-devdocs

This issue is a:

[ ] Bug
[X] Feature suggestion
[ ] Documentation issue
[ ] Other (Please Specify)

Environment

Question	Answer
Magento version
Operating System + version
node.js version (node -v)
npm version (npm -v)

Description

As a shopper I want to use input information at any point in the Venia store experience (e.g. checkout) that is clear, accessible, validated and consistent so that I can make a successful purchase.

• Store a local chance to input fields (form)
• Callback on updates (pre-validation)
• Local validation (multiple and at once)
• Render enabled/disabled state (based on conditions)
• Field layout/logic (groupings) ++minimum style/layout

**Checkout and My Account are dependencies

// Scenario: template

Expected result:

Form fields shown in context of a Venia checkout POC
Testing and documentation (as appropriate)
Full acessibility

Possible solutions:

[awilcoxa]

closing during backlog cleanup