uvwasi_path_symlink does not check old_path like others

[lum1n0us]

There are functions like uvwasi_path_rename() and uvwasi_path_link() that are similar to uvwasi_path_symlink(), as all three take old_path and new_path as input parameters. However, rename() and link() use uvwasi__resolve_path() to ensure that old_path and new_path are valid within the sandbox and accessible. This same verification does not occur in symlink(). This creates a potential issue where a caller could create a symlink that targets a file descriptor outside of the sandbox.