REORG: include: move cfgparse.h to haproxy/cfgparse.h

There's no point splitting the file in two since only cfgparse uses the
types defined there. A few call places were updated and cleaned up. All
of them were in C files which register keywords.

There is nothing left in common/ now so this directory must not be used
anymore.
diff --git a/src/mworker-prog.c b/src/mworker-prog.c
index f6e61ed..d0b9446 100644
--- a/src/mworker-prog.c
+++ b/src/mworker-prog.c
@@ -21,7 +21,7 @@
 #include <unistd.h>
 
 #include <haproxy/api.h>
-#include <common/cfgparse.h>
+#include <haproxy/cfgparse.h>
 #include <haproxy/errors.h>
 #include <haproxy/global.h>
 #include <haproxy/log.h>