cmake: Add debugger

- Depends on cppdap and jsoncpp.
- Add --debugger argument to enable the Debugger.
- Add --debugger-pipe argument for DAP traffics over named pipes.
- Support breakpoints by filenames and line numbers.
- Support exception breakpoints.
- Call stack shows filenames and line numbers.
- Show Cache Variables.
- Show the state of currently defined targets,
  tests and directories with their properties.
- Add cmakeVersion to DAP initialize response.
- Include unit tests.

Co-authored-by: Ben McMorran <bemcmorr@microsoft.com>

Source/cmDebuggerStackFrame.h

@@ -0,0 +1,33 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#pragma once
+
+#include "cmConfigure.h" // IWYU pragma: keep
+
+#include <atomic>
+#include <cstdint>
+#include <string>
+
+class cmListFileFunction;
+class cmMakefile;
+
+namespace cmDebugger {
+
+class cmDebuggerStackFrame
+{
+  static std::atomic<std::int64_t> NextId;
+  std::int64_t Id;
+  std::string FileName;
+  cmListFileFunction const& Function;
+  cmMakefile* Makefile;
+
+public:
+  cmDebuggerStackFrame(cmMakefile* mf, std::string sourcePath,
+                       cmListFileFunction const& lff);
+  int64_t GetId() const noexcept { return this->Id; }
+  std::string const& GetFileName() const noexcept { return this->FileName; }
+  int64_t GetLine() const noexcept;
+  cmMakefile* GetMakefile() const noexcept { return this->Makefile; }
+};
+
+} // namespace cmDebugger