Avoid passing RuleMessage by std::shared_ptr and use a reference instead.

- Avoids copying std::shared_ptr when lifetime of the RuleMessage
  is controlled by the caller.
  - The RuleMessage instance is created in RuleWithActions::evaluate and
    then used to call the overloaded version of this method that is
    specialized by subclasses.
  - Once the call to the overloaded method returns, the std::shared_ptr
    is destroyed as it's not stored by any of the callers, so it can
    be replaced with a stack variable and avoid paying the cost of
    copying the std::shared_ptr (and its control block that is
    guaranteed to be thread-safe and thus is not a straightforward
    pointer copy)
- Introduced RuleMessage::reset because this is required by
  RuleWithActions::performLogging when it's not the 'last log', the rule
  has multimatch and it's to be logged.
  - The current version is creating allocating another instance of
    RuleMessage on the heap to copy the Rule & Transaction related state
    while all the other members in the RuleMessage are set to their
    default values.
  - The new version leverages the existent, unused and incomplete
    function 'clean' (renamed as 'reset') to do this on the current
    instance.
    - Notice that the current code preserves the value of m_saveMessage,
      so 'reset' provides an argument for the caller to control whether
      this member should be reinitialized.

headers/modsecurity/rule_with_operator.h

@@ -47,8 +47,7 @@ class RuleWithOperator : public RuleWithActions {
 
     ~RuleWithOperator() override;
 
-    bool evaluate(Transaction *transaction,
-        std::shared_ptr<RuleMessage> rm) override;
+    bool evaluate(Transaction *transaction, RuleMessage &ruleMessage) override;
 
     void getVariablesExceptions(Transaction &t,
         variables::Variables *exclusion, variables::Variables *addition);
@@ -56,7 +55,7 @@ class RuleWithOperator : public RuleWithActions {
         variables::Variables *eclusion, Transaction *trans);
 
     bool executeOperatorAt(Transaction *trasn, const std::string &key,
-        const std::string &value, std::shared_ptr<RuleMessage> rm);
+        const std::string &value, RuleMessage &ruleMessage);
 
     static void updateMatchedVars(Transaction *trasn, const std::string &key,
         const std::string &value);