Make frameworks a linking style at cxx level

Created by: robbertvanginkel

Start replacement for #842. Some notes:

• The old approach included framewrorks at the apple package level, which introduced complications at the linking level. As the linker/compiler at a clang/ld level accept framework related arguments, implement these at the level of the cxx package.
• Instead of specifying a #framework flavor for dependencies, use the preferred_linkage and link_style arguments to controll if apple library will be a framework, dylib or static library.
• Split into a framework-bundle and framework-binary flavor for clariness.

Todo's:

• Modulemaps and umbrella headers
• Framework resources are not collected properly
• Embedding frameworks