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.cpp

@@ -267,3 +267,15 @@ std::string CScriptWitness::ToString() const
     }
     return ret + ")";
 }
+
+bool CScript::HasValidOps() const
+{
+    CScript::const_iterator it = begin();
+    while (it < end()) {
+        opcodetype opcode;
+        if (!GetOp(it, opcode) || opcode > 0xb9) {
+            return false;
+        }
+    }
+    return true;
+}

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