chore: Adding workflow to build Amplify for minimum Xcode

[ruisebas]

Description

This PR fixes the build_minimum_supported_swift_platforms.yml workflow so that we build each platform for the minimum supported Xcode version on each PR and push to the main branch:

• For iOS and macOS, the minimum supported Xcode version is 14.1.
• For watchOS and tvOS, the minimum supported Xcode version is 14.3 We're using 14.3.1 as that is the one available in the macos-13 GitHub runner.

Summary of changes:

• Creating a new target called Amplify-Build that only includes the Amplify plugins and no tests.
• Renaming build-amplify-package to build-scheme and making the scheme an argument
• Removing continue-on-error on the build step, as otherwise the workflow would report a success even if it failed.

General Checklist

• Added new tests to cover change, if needed
• Build succeeds with all target using Swift Package Manager
• All unit tests pass
• All integration tests pass
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)
• Documentation update for the change if required
• PR title conforms to conventional commit style
• New or updated tests include Given When Then inline code documentation and are named accordingly testThing_condition_expectation()
• If breaking change, documentation/changelog update with migration instructions

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[atierian]

❤️