REORG: include: move common/h1.h to haproxy/h1.h

The file was moved as-is. There was a wrong dependency on dynbuf.h
instead of buf.h which was addressed. There was no benefit to
splitting this between types and functions.
diff --git a/src/h1_htx.c b/src/h1_htx.c
index 83ebfb1..69472a6 100644
--- a/src/h1_htx.c
+++ b/src/h1_htx.c
@@ -12,7 +12,7 @@
 
 #include <haproxy/api.h>
 #include <common/cfgparse.h>
-#include <common/h1.h>
+#include <haproxy/h1.h>
 #include <haproxy/http.h>
 #include <common/htx.h>