Switch core library search from $LOAD_PATH scan to RbConfig-based lookup

Changed the mechanism for collecting Ruby core libraries to search directories based on RbConfig::CONFIG instead of scanning the entire $LOAD_PATH.

Author: shinokaro

lib/ocran/direction.rb

@@ -209,7 +209,10 @@ def construct(builder)
       # If requested, add all ruby standard libraries
       if @option.add_all_core?
         say "Will include all ruby core libraries"
-        @pre_env.load_path.each do |load_path|
+        RbConfig::CONFIG
+          .slice("rubylibdir", "sitelibdir", "vendorlibdir")
+          .values
+          .each do |load_path|
           path = Pathname.new(load_path)
           # Match the load path against standard library, site_ruby, and vendor_ruby paths
           path.to_posix.match(RUBY_LIBRARY_PATH_REGEX) do |m|