Fixes missing required fields in manifest.json

[clavery]

Description

Fixes validity issues with web app manifest

Types of Changes

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Documentation update
• Breaking change (could cause existing functionality to not work as expected)
• Other changes (non-breaking changes that does not fit any of the above)

Breaking changes include:

• Removing a public function or component or prop
• Adding a required argument to a function
• Changing the data type of a function parameter or return value
• Adding a new peer dependency to package.json

Changes

• fixes [BUG] Templated web app manifest is missing name,short_name #727 by using an available value for the name

How to Test-Drive This PR

• Generate a new app ./packages/pwa-kit-create-app/scripts/create-mobify-app.js
• verify app/static/manifest.json has correct values

Checklists

General

• [] Changes are covered by test cases
• CHANGELOG.md updated with a short description of changes (not required for documentation updates)

Accessibility Compliance

You must check off all items in one of the follow two lists:

• There are no changes to UI

or...

• Changes were tested with a Screen Reader (iOS VoiceOver or Android Talkback) and had no issues
• Changes comply with WCAG 2.0 guidelines levels A and AA
• Changes to common UI patterns and interactions comply with WAI-ARIA best practices

Localization

• Changes include a UI text update in the Retail React App (which requires translation)

[adamraya]

Thank you @clavery for identifying and fixing this issue!

Generated projects have been missing the short_name and name properties for a long time on the manifest.json.