Describe the bug
In convert_global_weights, no error raised if no global weights are converted in MonaiAlgo

To Reproduce
Server uses a different model configuration than client. Mismatching keys cause convert_global_weights to not convert any global weights causing later errors.

Expected behavior
Raise error if no weights are converted.

Screenshots
n/a

Environment

Ensuring you use the relevant python executable, please paste the output of:

python -c 'import monai; monai.config.print_debug_info()'

Additional context
dev branch