Add support for CMake builds

[Davit-G]

Added support for CMake builds, fetching v7.0.11 from the JUCE Github repository.

AAX compilation is not enabled but can be enabled according to the README.md build instructions.

[Davit-G]

Basic CMakeLists.txt files have been added, feel free to contribute / edit if there is anything wrong 👍

[hollance]

Hey, thanks for adding CMake support. I left a few small comments on your commits.

Could you also add the following lines to generate dSYM files for Xcode release builds?

set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -g")
set(CMAKE_XCODE_ATTRIBUTE_GCC_GENERATE_DEBUGGING_SYMBOLS[variant=Release] "YES")
set(CMAKE_XCODE_ATTRIBUTE_DEBUG_INFORMATION_FORMAT[variant=Release] "dwarf-with-dsym")
set(CMAKE_XCODE_ATTRIBUTE_DEPLOYMENT_POSTPROCESSING[variant=Release] "YES")

Thanks!