Everywhere: Replace a bundle of dbg with dbgln.

These changes are arbitrarily divided into multiple commits to make it
easier to find potentially introduced bugs with git bisect.

The modifications in this commit were automatically made using the
following command:

    find . -name '*.h' -exec sed -i -E 's/dbg\(\) << ("[^"{]*");/dbgln\(\1\);/' {} \;

Libraries/LibRegex/RegexDebug.h

@@ -64,7 +64,7 @@ public:
         for (;;) {
             auto* opcode = bytecode.get_opcode(state);
             if (!opcode) {
-                dbg() << "Wrong opcode... failed!";
+                dbgln("Wrong opcode... failed!");
                 return;
             }