Add a valid opcode sanity check to CScript

Added a function in CScript that checks if the script contains valid opcodes.

Add a test for that function

src/script/script.h

@@ -630,6 +630,9 @@ public:
     bool IsPushOnly(const_iterator pc) const;
     bool IsPushOnly() const;
 
+    /** Check if the script contains valid OP_CODES */
+    bool HasValidOps() const;
+
     /**
      * Returns whether the script is guaranteed to fail at execution,
      * regardless of the initial stack. This allows outputs to be pruned