[feature] Add more fine grained control to CMake project

[WebmasterTD]

It would be useful to add more option flags to the CMake project, enabling a more granular build process, enabling a more granular build process. This would be useful when importing the library into other projects, allowing for the exclusion of unnecessary targets, such as examples and extra components.

[Theldus]

Hi @WebmasterTD, Since wsServer is such a small project with a quick build time, I've never really bothered with this, but if you'd like to work on it, I'd gladly accept a PR, ;-).