(osx) Make Cordova OSX build successfully on AppleSilicon target.

[bpresles]

Platforms affected

macOS ARM64 (AppleSilicon).

Motivation and Context

Build failed when targeting AppleSilicon because of using old prototype for objc_msgSend.

Description

Closes #104

• Added "arm64" as valid architecture
• Changed calls to objc_msgSend() to use new cast based prototype.

Testing

• Built the library on XCode 12 with support for Universal Binaries and AppleSilicon
• Tested the universal binary build of the library on a Cordova OS X project

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

[motla]

@erisu could you please merge this one then make a release?
otherwise it is blocking compilation fail for every dev using the updated XCode....
thanks

cordova platform add https://github.com/bpresles/cordova-osx.git#AppleSilicon

[brodybits]

I highly recommend that you followup on Slack and on the dev mailing list, please follow links from the footer of cordova.io or cordova.apache.org, and try again if you don't hear anything. Unfortunately the maintainers have been pretty overloaded over the past couple years.

[NiklasMerz]

Builds fine on M1 for me. I am not deep enough into ObjC to judge the code but it looks good to me.

[fortuna]

@bpresles are you able to merge the PR? It's been approved.