Fix the artifacts locate function #12

The artifacts locate function https://github.com/glihm/kipt/blob/main/src/declare.rs#L181 has for now two problems:

1. The recursion is not well made and then only parse the first sub-directory only.
2. The path in the Lua file is relative to where kipt is executed. We need better error message to indicate that the file is not found because of paths.