Release notes

Features:

• added list configs command to list configuration files
• added option --context-replacement to replace context selection
• added license information to cbuild.yml files
• introduced optional flag when requiring a layer by its type
• check file references portability
• support dry-running generators

Bugfixes:

• fixed handling of duplicated packs
• fixed toolchain redefinition from command line --toolchain
• fixed list layers: update connections validation rules
• fixed list layers: consider candidate layers as optional by default
• updated cdefault content
• updated CLANG support
• updated default linker scripts