Separate conan install from autodetection

[czoido]

As Conan is adding more arguments to support new features as lockfiles or build and host profiles, this features usually collide with the cmake-conan settings auto-detection. This PR adds some functions to decouple the auto-deteccion from the call to conan install so instead of just calling to conan_cmake_run, these functions can be called separately (conan_cmake_run is still there but is recommended to use just for basic cases, not for using new Conan features):

• Creation of the conanfile.txt on the fly: conan_cmake_configure
• Settings auto-detection: conan_cmake_autodetect
• Pure conan install wrapper: conan_cmake_install all the input arguments from conan install are mapped to this cmake function.

A CMakeLists.txt using these functions would look like this:

cmake_minimum_required(VERSION 3.5)
project(FormatOutput CXX)
list(APPEND CMAKE_MODULE_PATH ${CMAKE_BINARY_DIR})
list(APPEND CMAKE_PREFIX_PATH ${CMAKE_BINARY_DIR})
add_definitions("-std=c++11")
include(conan.cmake)

# arguments: REQUIRES, GENERATORS, BUILD_REQUIRES, IMPORTS, OPTIONS
conan_cmake_configure(REQUIRES fmt/6.1.2 GENERATORS cmake_find_package)

conan_cmake_autodetect(settings)

# arguments: UPDATE NO_IMPORTS PATH_OR_REFERENCE REFERENCE REMOTE LOCKFILE LOCKFILE_OUT LOCKFILE_NODE_ID 
# INSTALL_FOLDER GENERATOR BUILD ENV ENV_HOST ENV_BUILD OPTIONS_HOST OPTIONS 
# OPTIONS_BUILD PROFILE PROFILE_HOST PROFILE_BUILD SETTINGS SETTINGS_HOST SETTINGS_BUILD
conan_cmake_install(PATH_OR_REFERENCE .
                    BUILD missing
                    REMOTE conan-center
                    SETTINGS ${settings})

find_package(fmt)

add_executable(main main.cpp)
target_link_libraries(main fmt::fmt)

or including conanbuildinfo.cmake

cmake_minimum_required(VERSION 3.5)
project(FormatOutput)
add_definitions("-std=c++11")
include(conan.cmake)

conan_cmake_configure(REQUIRES fmt/6.1.2)

conan_cmake_autodetect(settings)

conan_cmake_install(PATH_OR_REFERENCE .
                    GENERATOR cmake gcc
                    SETTINGS ${settings}
                    BUILD missing
                    REMOTE conan-center)

include(${CMAKE_BINARY_DIR}/conanbuildinfo.cmake)
conan_basic_setup(TARGETS)

add_executable(main main.cpp)
target_link_libraries(main CONAN_PKG::fmt)

This PR some refactors from the previous state.

Closes:

• Adding an argument to pass a lockfile #294
• Support lockfiles in conan_cmake_run() #271
• Automatically created conanfile.txt shows different generators #276

[memsharded]

Maybe try to use functions with returns, instead of macros.