Update kconfiglib to upstream version and replace mconf-idf

Special thanks to @ulfalizer for the helpful suggestions regarding
kconfiglib.

"rsource" option is available for relative path includes
Closes https://github.com/espressif/esp-idf/issues/4064

tools/check_python_dependencies.py

@@ -55,6 +55,10 @@ if __name__ == "__main__":
     with open(args.requirements) as f:
         for line in f:
             line = line.strip()
+            # pkg_resources.require() cannot handle the full requirements file syntax so we need to make
+            # adjustments for options which we use.
+            if line.startswith('file://'):
+                line = os.path.basename(line)
             try:
                 pkg_resources.require(line)
             except Exception: