[FEATURE] Add support to MacOS

[rignaneseleo]

Please add support to MacOS so that we can use the library on that platform too.

[ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: MissingPluginException(No implementation found for method sendCrash on channel flutter_bugfender)
#0      MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:332:7)
<asynchronous suspension>
#1      MethodChannelFlutterBugfender.sendCrash.<anonymous closure> (package:flutter_bugfender/flutter_bugfender_method_channel.dart:79:13)
<asynchronous suspension>
#2      FlutterBugfender.handleUncaughtErrors.<anonymous closure> (package:flutter_bugfender/flutter_bugfender.dart:83:7)
<asynchronous suspension>

[rignaneseleo]

I think the right behavior here for such a library should be to print a warning and keep going on, ignoring all the remote logs.

[solshark]

Super relevant for me.