Default platform, `make update`, `forwardEnv` setting, ...

New features:

• Support for new style CMake
• Add make update feature, closes #22 (closed)
• Propagate environment variables with forwardEnv setting

Fixes:

• Better kerberos token check (require CERN.CH principal)
• If no command is given to build-env, print environment
• Support Gaudi versions with old-style CMake

Improvements:

• Indent multi-line logging messages on the console
• Speed up run-env by removing call to config.py
• Update default platform to x86_64_v2-centos7-gcc10-opt
• Use latest stable LbEnv 2086

Internal changes:

• Clean up CI: platform handling and legacy support
• Improve data package - container project relationship
• Use exec in wrapper scripts (reduce processes)