Implement requiresMainQueueSetup in RCTTVNavigationEventEmitter
Implement requiresMainQueueSetup in RCTTVNavigationEventEmitter

Summary:
Fix the following warning:

> Module RCTTVNavigationEventEmitter requires main queue setup since it overrides `init` but doesn't implement `requiresMainQueueSetup`. In a future release React Native will default to initializing all native modules on a background thread unless explicitly opted-out of.

Trivial change.

[IOS] [MINOR] [RCTTVNavigationEventEmitter] - Implement `requiresMainQueueSetup` in `RCTTVNavigationEventEmitter`
Closes https://github.com/facebook/react-native/pull/16915

Differential Revision: D6394636

Pulled By: shergin

fbshipit-source-id: 3981655832715e73e93ef917d987e25097029b84

exponent/react-native,ptmt/react-native-macos,rickbeerendonk/react-native,ptmt/react-native-macos,myntra/react-native,jevakallio/react-native,exponentjs/react-native,kesha-antonov/react-native,javache/react-native,hammerandchisel/react-native,myntra/react-native,myntra/react-native,hoastoolshop/react-native,hoastoolshop/react-native,rickbeerendonk/react-native,Bhullnatik/react-native,dikaiosune/react-native,exponent/react-native,arthuralee/react-native,hammerandchisel/react-native,javache/react-native,exponentjs/react-native,jevakallio/react-native,Bhullnatik/react-native,pandiaraj44/react-native,myntra/react-native,javache/react-native,pandiaraj44/react-native,jevakallio/react-native,rickbeerendonk/react-native,exponent/react-native,hoangpham95/react-native,facebook/react-native,pandiaraj44/react-native,Bhullnatik/react-native,rickbeerendonk/react-native,ptmt/react-native-macos,javache/react-native,dikaiosune/react-native,exponent/react-native,dikaiosune/react-native,janicduplessis/react-native,dikaiosune/react-native,facebook/react-native,hoangpham95/react-native,facebook/react-native,exponentjs/react-native,hoastoolshop/react-native,myntra/react-native,exponent/react-native,facebook/react-native,hoangpham95/react-native,janicduplessis/react-native,hammerandchisel/react-native,pandiaraj44/react-native,dikaiosune/react-native,exponentjs/react-native,jevakallio/react-native,hoangpham95/react-native,jevakallio/react-native,hammerandchisel/react-native,javache/react-native,hoangpham95/react-native,pandiaraj44/react-native,exponent/react-native,exponentjs/react-native,arthuralee/react-native,janicduplessis/react-native,kesha-antonov/react-native,hoastoolshop/react-native,facebook/react-native,exponentjs/react-native,myntra/react-native,jevakallio/react-native,janicduplessis/react-native,kesha-antonov/react-native,hammerandchisel/react-native,exponentjs/react-native,rickbeerendonk/react-native,ptmt/react-native-macos,rickbeerendonk/react-native,rickbeerendonk/react-native,arthuralee/react-native,myntra/react-native,javache/react-native,myntra/react-native,Bhullnatik/react-native,exponent/react-native,Bhullnatik/react-native,facebook/react-native,kesha-antonov/react-native,arthuralee/react-native,kesha-antonov/react-native,Bhullnatik/react-native,exponent/react-native,facebook/react-native,hoangpham95/react-native,jevakallio/react-native,myntra/react-native,kesha-antonov/react-native,jevakallio/react-native,jevakallio/react-native,facebook/react-native,ptmt/react-native-macos,pandiaraj44/react-native,kesha-antonov/react-native,arthuralee/react-native,hoastoolshop/react-native,exponentjs/react-native,hoangpham95/react-native,javache/react-native,ptmt/react-native-macos,pandiaraj44/react-native,janicduplessis/react-native,janicduplessis/react-native,hoastoolshop/react-native,hoastoolshop/react-native,hammerandchisel/react-native,Bhullnatik/react-native,hoangpham95/react-native,ptmt/react-native-macos,hoastoolshop/react-native,rickbeerendonk/react-native,javache/react-native,hammerandchisel/react-native,Bhullnatik/react-native,dikaiosune/react-native,ptmt/react-native-macos,kesha-antonov/react-native,janicduplessis/react-native,rickbeerendonk/react-native,pandiaraj44/react-native,kesha-antonov/react-native,javache/react-native,dikaiosune/react-native,dikaiosune/react-native,hammerandchisel/react-native,janicduplessis/react-native,facebook/react-native