[#66] Implement support for multiple meshes

config/Sources.cmake

include/vkcv/Buffer.hpp

include/vkcv/Core.hpp

include/vkcv/DescriptorConfig.hpp

include/vkcv/DrawcallRecording.hpp

projects/cmd_sync_test/src/main.cpp

projects/first_mesh/src/main.cpp

projects/first_triangle/src/main.cpp

src/vkcv/Core.cpp

src/vkcv/DescriptorConfig.cpp

src/vkcv/DrawcallRecording.cpp