Fix crash; fs event received /w langauge file empty
Fix crash; fs event received /w langauge file empty

It was common, at least for me, to experience a crash produced
when running the `matrix-react-sdk/scripts/gen-i18n.js` script
because when writing en_EN.json (via the script or otherwise)
choikdar would receive an event and cause the file to be read,
but the file would be empty when clearly it wasn't.

This would happen even when doing an atomic write in gen-i18n.

The fix adds a debounce as a workaround.

vector-im/vector-web,vector-im/vector-web,vector-im/vector-web,vector-im/riot-web,vector-im/riot-web,vector-im/vector-web,vector-im/riot-web,vector-im/riot-web,vector-im/vector-web,vector-im/riot-web,vector-im/riot-web