Added MIDL headers (_i.h) to Visual Studio gitignore

CSharp.gitignore

@@ -19,6 +19,7 @@ TestResults
 x64/
 *_i.c
 *_p.c
+*_i.h
 *.ilk
 *.meta
 *.obj

Global/VisualStudio.gitignore

@@ -19,6 +19,7 @@ build/
 
 *_i.c
 *_p.c
+*_i.h
 *.ilk
 *.meta
 *.obj

VB.Net.gitignore

@@ -20,6 +20,7 @@ obj/
 x64/
 *_i.c
 *_p.c
+*_i.h
 *.ilk
 *.meta
 *.obj