Xcode 12.0 conformance

Adds two new options for Xcode 12 and above:

• include_dSYMs
• include_BCSymbolMaps

include_bitcode is no longer required == optional

Example:

  create_xcframework(
    scheme: 'iOSModule',
    workspace: 'XCFramework.xcworkspace',
    include_dSYMs: true, // optional, default: true
    include_BCSymbolMaps: true, // optional, default: true
    include_bitcode: true, // optional, default: true
    destinations: ['iOS', 'maccatalyst'],
    xcframework_output_directory: 'Products/xcframeworks'
  )

or simplified version of the above (default) case:

  create_xcframework(
    scheme: 'iOSModule',
    workspace: 'XCFramework.xcworkspace',
    destinations: ['iOS', 'maccatalyst'],
    xcframework_output_directory: 'Products/xcframeworks'
  )