Add CMake build with package configuration.

[MichaelCoutlakis-Peralex]

• Add CMake build with install and package config.
• Add missing includes (MSVC)

Main reason for this PR was to add CMake install capability.

Note that I recommend a target name like eleobert::dbscan rather than dbscan::dbscan as this allows, for example, several dbscan targets to be built into the same benchmark application.

Result:

find_package(eleobert-dbscan CONFIG REQUIRED)

target_link_libraries(${PROJECT_NAME}
	PRIVATE
	eleobert::dbscan
)

#include <eleobert/dbscan.hpp>