GH-1059: Add VALIDATE_WORKSPACE setting to XcodeProj

[dpogue]

Platforms affected

iOS

Motivation and Context

Closes GH-1059

Description

In Xcode 12, if an app is linked against .framework files with multiple architectures, it will generate an error about embedded framework mismatches. Declaring this property (even with its default value of NO) resolves the issue.

Testing

CI passing

Checklist

• [x] I've run the tests to see all new and existing tests pass
• [x] If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)

[JoeMeeks]

@dpogue can the yes/no or true/false value of VALIDATE_WORKSPACE be assigned in config.xml?

[dpogue]

can the yes/no or true/false value of VALIDATE_WORKSPACE be assigned in config.xml?

No