[react-datepicker] Fix callback signatures
[react-datepicker] Fix callback signatures

The signatures for onChange, onBlur, and onFocus were wrong.

progre/DefinitelyTyped,chrootsu/DefinitelyTyped,AgentME/DefinitelyTyped,georgemarshall/DefinitelyTyped,GiedriusGrabauskas/DefinitelyTyped,micurs/DefinitelyTyped,mcrawshaw/DefinitelyTyped,jimthedev/DefinitelyTyped,abbasmhd/DefinitelyTyped,benliddicott/DefinitelyTyped,chrootsu/DefinitelyTyped,borisyankov/DefinitelyTyped,zuzusik/DefinitelyTyped,arusakov/DefinitelyTyped,nycdotnet/DefinitelyTyped,georgemarshall/DefinitelyTyped,rolandzwaga/DefinitelyTyped,isman-usoh/DefinitelyTyped,ashwinr/DefinitelyTyped,aciccarello/DefinitelyTyped,alexdresko/DefinitelyTyped,progre/DefinitelyTyped,jimthedev/DefinitelyTyped,georgemarshall/DefinitelyTyped,GiedriusGrabauskas/DefinitelyTyped,AbraaoAlves/DefinitelyTyped,zuzusik/DefinitelyTyped,dsebastien/DefinitelyTyped,aciccarello/DefinitelyTyped,alexdresko/DefinitelyTyped,QuatroCode/DefinitelyTyped,YousefED/DefinitelyTyped,minodisk/DefinitelyTyped,georgemarshall/DefinitelyTyped,benishouga/DefinitelyTyped,AgentME/DefinitelyTyped,amir-arad/DefinitelyTyped,borisyankov/DefinitelyTyped,YousefED/DefinitelyTyped,AgentME/DefinitelyTyped,aciccarello/DefinitelyTyped,johan-gorter/DefinitelyTyped,laurentiustamate94/DefinitelyTyped,markogresak/DefinitelyTyped,magny/DefinitelyTyped,benishouga/DefinitelyTyped,dsebastien/DefinitelyTyped,isman-usoh/DefinitelyTyped,benishouga/DefinitelyTyped,nycdotnet/DefinitelyTyped,QuatroCode/DefinitelyTyped,arusakov/DefinitelyTyped,ashwinr/DefinitelyTyped,jimthedev/DefinitelyTyped,AgentME/DefinitelyTyped,rolandzwaga/DefinitelyTyped,smrq/DefinitelyTyped,AbraaoAlves/DefinitelyTyped,mcrawshaw/DefinitelyTyped,mcliment/DefinitelyTyped,johan-gorter/DefinitelyTyped,abbasmhd/DefinitelyTyped,smrq/DefinitelyTyped,magny/DefinitelyTyped,arusakov/DefinitelyTyped,minodisk/DefinitelyTyped,AbraaoAlves/DefinitelyTyped,one-pieces/DefinitelyTyped,zuzusik/DefinitelyTyped