utils: hasKey(), getKeyOrEmpty(), getAll(): Take params as references

Somehow, the fact that multimap was being copyied slipped through.

utils.h

@@ -20,13 +20,13 @@ std::string strreplace(const std::string &str, const std::string &search, const
 std::string html_xss(std::string_view str);
 std::string getenv(const std::string &key);
 
-template <class T, class U> bool hasKey(const std::map<T, U> &map, T key)
+template <class T, class U> bool hasKey(const std::map<T, U> &map, const T &key)
 {
 	auto k = map.find(key);
 	return k != map.end();
 }
 
-template <class T, class U> U getKeyOrEmpty(const std::map<T, U> &map, T key)
+template <class T, class U> U getKeyOrEmpty(const std::map<T, U> &map, const T &key)
 {
 	auto k = map.find(key);
 	if(k != map.end())
@@ -36,7 +36,7 @@ template <class T, class U> U getKeyOrEmpty(const std::map<T, U> &map, T key)
 	return U();
 }
 
-template <class T, class U> U getKeyOrEmpty(std::multimap<T, U> map, T key)
+template <class T, class U> U getKeyOrEmpty(const std::multimap<T, U> &map, const T &key)
 {
 	auto k = map.find(key);
 	if(k != map.end())
@@ -46,7 +46,7 @@ template <class T, class U> U getKeyOrEmpty(std::multimap<T, U> map, T key)
 	return U();
 }
 
-template <class T, class U> std::vector<U> getAll(std::multimap<T, U> map, T key)
+template <class T, class U> std::vector<U> getAll(const std::multimap<T, U> &map, const T &key)
 {
 	std::vector<U> result;
 	auto range = map.equal_range(key);