Modernize forms library

[pjm17971]

Umbrella issue for work on forms library:

• Move library to Typescript
• Remove flexbox-react code
• Update to react-bootstrap (fix icons)
• Add storybook for development, testing and docs
• Update to latest version of react-select, combine with react-window
• Overhaul build setup (rollup)

Components that need to work:

• TextEdit
• TextArea
• DateEdit
• Chooser (based on react-select)
• AsyncChooser (based on react-select)
• TagsEdit (based on react-select)

Additional components

• List and list HOC
• Views

Covered examples:

• Basic form with tri-state edit modes (always, selected and never)
• Dynamic changing form
• List contact example

Storybook:

• Initial setup so we can add stories in Typescript
• Snapshot testing
• Docs