Fix rights checks across the codebase.

* Fix path_open granting more rights than requested
* Add missing rights checks in: fd_fdstat_set_flags, fd_filestat_get, poll_oneoff
* Fix `open_scratch_directory` not requesting any rights.
* Properly request needed rights in various tests
* Add some extra trace-level logging
* Remove a no-op restriction of rights to the ones returned by
  `determine_type_rights`. It was redundant, because `FdEntry:from`
  internally also called `determine_type_rights` and only dropped some of them.

crates/test-programs/wasi-tests/src/bin/fd_readdir.rs

@@ -90,7 +90,10 @@ unsafe fn test_fd_readdir(dir_fd: wasi::Fd) {
         0,
         "file",
         wasi::OFLAGS_CREAT,
-        wasi::RIGHTS_FD_READ | wasi::RIGHTS_FD_WRITE,
+        wasi::RIGHTS_FD_READ
+            | wasi::RIGHTS_FD_WRITE
+            | wasi::RIGHTS_FD_READDIR
+            | wasi::RIGHTS_FD_FILESTAT_GET,
         0,
         0,
     )