Upgraded facebook sdk ios bindings to 18.0.0

[thisisthekap]

Fixes #103

I needed to change the way the dependency is referenced. This is because facebook decided to move from static frameworks to dynamic frameworks.

Thanks @rolfbjarne for your assistance on resolving this issue.#

See #96 and dotnet/macios#23282 for reference.

[mstancombe]

@thisisthekap thanks for the work on this. I've tweaked my project using the same changes as the PR, and can now build just fine, but pushing to the app store is failing with

The bundle 'com.facebook.sdk.FBAEMKit' at bundle path 'Payload/MyDotnetSample.Mobile.app/Frameworks/MauiFacebook.framework/Frameworks/FBAEMKit.framework' is not signed using an Apple submission certificate.

The app has previously built and been submittable to the app store, so I think the cert / provisioning profile being used in dotnet publish is ok. Any idea why it might not be getting down to the facebook dependency?

[thisisthekap]

@mstancombe I already fixed this issue for my repository https://github.com/thisisthekap/Tonestro.Maui.FacebookSlim.iOS

The commit I did some seconds ago adds the fix to this PR as well.

[thisisthekap]

@mstancombe Please add your feedback to this PR once you tested it.

[mstancombe]

It published to test flight! removing the embed framework stuff from the proj file as per the change worked :)
Thanks so much @thisisthekap 🙏