Merging address autocompletion feature to develop branch.

See original PR: #3071

Description

Merging address autocompletion feature to develop branch. The changes included are from previously approved PRs.
#2614
#2767
#2886
#2981
#3209

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

• New environment variable (GOOGLE_CLOUD_API_KEY) that allows customers to enable the address autocompletion feature in checkout (and any address fields)
• Introduction of Shopper Configuration SCAPI endpoint and usage in checkout
• Address suggestions from Google Maps Platform are displayed to the user upon 3 or more characters in the input field
• Address autocompletion for address fields upon choosing an address suggestion from the dropdown

How to Test-Drive This PR

• Add an item to the cart and go to checkout. Fill out your contact information to go to shipping address section.
• Country is auto-selected (United States), can change if you want.
• Start typing 3 or more characters in the Address field.
• Address Suggestions dropdown should be displayed to the buyer, with an option to temporarily close it (X icon).
• Upon choosing an address suggestion, the address fields should be automatically populated.
• Try the same with billing address (specify that it's different from shipping address).
• Checkout can be completed as expected.

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)