docs: begin to setup main structure and write BlockSS

backend/src/bs-utility.cpp

@@ -0,0 +1,13 @@
+#include "bs-utility.h"
+
+BlockingStringStream &BlockingStringStream::getline(std::string &str,
+                                                    char delim) {
+  std::unique_lock<std::mutex> lock(mutex);
+
+  // Wait until data is available
+  condition.wait(lock, [this] { return internalStream.peek() != EOF; });
+
+  std::getline(internalStream, str, delim);
+
+  return *this;
+}