Adding CMakeLists.txt for cpp version

[micaah42]

Hello there,

I added a minimal CMakeLists.txt to make it easier to include this repository in cmake driven projects.

You can build a static library using:

cd cpp
mkdir build && cd build
cmake ..
make

Or include in other projects like this:

include(FetchContent)

FetchContent_Declare(qrcodegen
    SOURCE_SUBDIR cpp
    GIT_REPOSITORY [email protected]:micaah42/QR-Code-generator.git
    GIT_TAG master
)
FetchContent_MakeAvailable(qrcodegen)

If you have any notes or want something fixed let me know :)