Fedbiomed

- fix `fedbiomed_vpn` failure due to time race under certain circumstance

- introduce new communication architecture based on gRPC
- introduce communication TLS encryption for automatic protection from passive MITM
- redesign researcher side's `Requests` for better performance and robustness
- add support for weighted average with secure aggregation
- fix secure aggregation bug when using more than 2 nodes
- fix tune DecLearn sample notebook parameters for demonstrating high accuracy
- fix misc error in checking coherence of node side validation parameters
- fix misc errors in notebooks

- improve import interface for DecLearn optimizers
- improve training plan dependencies import on researcher side
- fix error when using global model node side testing due to node state bug
- fix node GUI dependencies
- fix `configure_conda` failing silently
- fix misc issues in documentation and notebooks
- fix web site download link for tutorial notebooks

- fix failure due to erroneous researcher side data quality checks: remove currently useless data quality checks

- fix support for per-layer learning rate for PyTorch models

- update software dependencies and implement more strict package version checks
- fix docker containers build failures due to outdated package dependencies