AK: Add a StringView class.

AK/StringView.h

@@ -0,0 +1,25 @@
+#pragma once
+
+class StringView {
+public:
+    StringView() { }
+    StringView(const char* characters, int length) : m_characters(characters), m_length(length) { }
+    StringView(const unsigned char* characters, int length) : m_characters((const char*)characters), m_length(length) { }
+    StringView(const char* cstring)
+        : m_characters(cstring)
+    {
+        if (cstring) {
+            while (*(cstring++))
+                ++m_length;
+        }
+    }
+
+    bool is_empty() const { return m_length == 0; }
+    const char* characters() const { return m_characters; }
+    int length() const { return m_length; }
+    char operator[](int index) const { return m_characters[index]; }
+
+private:
+    const char* m_characters { nullptr };
+    int m_length { 0 };
+};