[meta,cmake] Restructure project and introduce CMake tooling

Rearrange project to conform to current best-practices in modern C++ repo organization.

Introduce initial configuration file for the CMake meta-build system, based on the restructured organization.

cmake/Findcrypto.cmake

-# https://github.com/aws/aws-sdk-cpp/blob/main/cmake/Findcrypto.cmake
-# - Try to find LibCrypto include dirs and libraries
-#
-# Usage of this module as follows:
-#
-#     find_package(crypto)
-#
-# Variables used by this module, they can change the default behaviour and need
-# to be set before calling find_package:
-#
-# Variables defined by this module:
-#
-#  crypto_FOUND             System has libcrypto, include and library dirs found
-#  crypto_INCLUDE_DIR       The crypto include directories.
-#  crypto_LIBRARY           The crypto library, depending on the value of BUILD_SHARED_LIBS.
-#  crypto_SHARED_LIBRARY    The path to libcrypto.so
-#  crypto_STATIC_LIBRARY    The path to libcrypto.a
-
-# the next branch exists purely for cmake compatibility with versions older than 3.15. Please do not remove it before
-# we baseline on a newer version. It does not like duplicate target declarations. Work around that by checking it isn't
-# defined first.
-if (TARGET crypto OR TARGET AWS::crypto)
-    if (TARGET crypto)
-        set(TARGET_NAME "crypto")
-    else()
-        set(TARGET_NAME "AWS::crypto")
-    endif()
-
-    get_target_property(crypto_INCLUDE_DIR ${TARGET_NAME} INTERFACE_INCLUDE_DIRECTORIES)
-    message(STATUS "S2N found target: ${TARGET_NAME}")
-    message(STATUS "crypto Include Dir: ${crypto_INCLUDE_DIR}")
-    set(CRYPTO_FOUND true)
-    set(crypto_FOUND true)
-else()
-    find_path(crypto_INCLUDE_DIR
-            NAMES openssl/crypto.h
-            HINTS
-            "${CMAKE_PREFIX_PATH}"
-            "${CMAKE_INSTALL_PREFIX}"
-            PATH_SUFFIXES include
-    )
-
-    find_library(crypto_SHARED_LIBRARY
-            NAMES libcrypto.so libcrypto.dylib
-            HINTS
-            "${CMAKE_PREFIX_PATH}"
-            "${CMAKE_INSTALL_PREFIX}"
-            PATH_SUFFIXES build/crypto build lib64 lib
-    )
-
-    find_library(crypto_STATIC_LIBRARY
-            NAMES libcrypto.a
-            HINTS
-            "${CMAKE_PREFIX_PATH}"
-            "${CMAKE_INSTALL_PREFIX}"
-            PATH_SUFFIXES build/crypto build lib64 lib
-    )
-
-    if (NOT crypto_LIBRARY)
-        if (BUILD_SHARED_LIBS)
-            set(crypto_LIBRARY ${crypto_SHARED_LIBRARY})
-        else()
-            if (crypto_STATIC_LIBRARY)
-                set(crypto_LIBRARY ${crypto_STATIC_LIBRARY})
-            else()
-                set(crypto_LIBRARY ${crypto_SHARED_LIBRARY})
-            endif()
-        endif()
-    endif()
-
-    include(FindPackageHandleStandardArgs)
-    find_package_handle_standard_args(crypto DEFAULT_MSG
-            crypto_LIBRARY
-            crypto_INCLUDE_DIR
-    )
-
-    mark_as_advanced(
-            crypto_ROOT_DIR
-            crypto_INCLUDE_DIR
-            crypto_LIBRARY
-            crypto_SHARED_LIBRARY
-            crypto_STATIC_LIBRARY
-    )
-
-    # some versions of cmake have a super esoteric bug around capitalization differences between
-    # find dependency and find package, just avoid that here by checking and
-    # setting both.
-    if(CRYPTO_FOUND OR crypto_FOUND)
-        set(CRYPTO_FOUND true)
-        set(crypto_FOUND true)
-
-        message(STATUS "LibCrypto Include Dir: ${crypto_INCLUDE_DIR}")
-        message(STATUS "LibCrypto Shared Lib:  ${crypto_SHARED_LIBRARY}")
-        message(STATUS "LibCrypto Static Lib:  ${crypto_STATIC_LIBRARY}")
-        if (NOT TARGET crypto AND
-        (EXISTS "${crypto_LIBRARY}")
-        )
-            set(THREADS_PREFER_PTHREAD_FLAG ON)
-            find_package(Threads REQUIRED)
-            add_library(AWS::crypto UNKNOWN IMPORTED)
-            set_target_properties(AWS::crypto PROPERTIES
-                    INTERFACE_INCLUDE_DIRECTORIES "${crypto_INCLUDE_DIR}")
-            set_target_properties(AWS::crypto PROPERTIES
-                    IMPORTED_LINK_INTERFACE_LANGUAGES "C"
-                    IMPORTED_LOCATION "${crypto_LIBRARY}")
-            add_dependencies(AWS::crypto Threads::Threads)
-        endif()
-    endif()
-
-endif()