Move CMake directory (#4997)

cmake/RippledValidatorKeys.cmake

@@ -0,0 +1,22 @@
+option (validator_keys "Enables building of validator-keys-tool as a separate target (imported via FetchContent)" OFF)
+
+if (validator_keys)
+  git_branch (current_branch)
+  # default to tracking VK master branch unless we are on release
+  if (NOT (current_branch STREQUAL "release"))
+    set (current_branch "master")
+  endif ()
+  message (STATUS "tracking ValidatorKeys branch: ${current_branch}")
+
+  FetchContent_Declare (
+    validator_keys_src
+    GIT_REPOSITORY https://github.com/ripple/validator-keys-tool.git
+    GIT_TAG        "${current_branch}"
+  )
+  FetchContent_GetProperties (validator_keys_src)
+  if (NOT validator_keys_src_POPULATED)
+    message (STATUS "Pausing to download ValidatorKeys...")
+    FetchContent_Populate (validator_keys_src)
+  endif ()
+  add_subdirectory (${validator_keys_src_SOURCE_DIR} ${CMAKE_BINARY_DIR}/validator-keys)
+endif ()