fix(push): fix payload content-available crash

[sithwarrior]

Changes notificationMessage from NSDictionary to NSMutableDictionary and the content-availble hander changes userinfo to a mutableCopy

Description

same as above

Related Issue

fixes #314

Motivation and Context

This fixes the app crashing at

cordova-plugin-push/src/ios/PushPlugin.m

Line 497 in 12a5b71

[(NSMutableDictionary *) self.notificationMessage removeObjectForKey:@"applicationState"];

How Has This Been Tested?

receive a push payload with content-available:1

Screenshots (if appropriate):

Types of changes

• [ x] Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [ x] My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• [ x] I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• [ x] All new and existing tests passed.

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.