fix(ios): correctly append exif on iOS 14

[jcesarmobile]

Platforms affected

ios

Motivation and Context

on iOS 14 if using <preference name="CameraUsesGeolocation" value="true" /> when trying to append the gps data to the exif the image gets corrupted

closes #674

Description

Testing

Used https://github.com/guilhermefarias/cordova-exif plugin to check the exif of the image after capturing on the provided sample app https://github.com/R4yYx/IOSSampleAPP

Checklist

• I've run the tests to see all new and existing tests pass
• I added automated test coverage as appropriate for this change
• Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• 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)
• I've updated the documentation if necessary

[timbru31]

LGTM - out of curiosity, do we have any evidence why a copy of the data is required?

[jcesarmobile]

No, but debugging I noticed the data became null/empty on the second CGImageSourceCreateWithData call, while calling it only once didn't, so I used a copy of the data to create the source and the original data for the destination.