abstract aways file2rwmapped construction to lower visibility

solanaceae/ngc_ft1_sha1/file_constructor.hpp

@@ -0,0 +1,9 @@
+#pragma once
+
+#include <solanaceae/file/file2.hpp>
+
+#include <memory>
+#include <string_view>
+
+std::unique_ptr<File2I> construct_file2_rw_mapped(std::string_view file_path, int64_t file_size = -1);
+