Resources extension: TemporaryDirectory: Restore mint permissions before closing context to avoid AccessDeniedException

[jbduncan]

Consider introducing this fix that the JUnit 5 team accepted for their own TempDir, to our own TemporaryDirectory class. It will allow tests that use our TemporaryDirectory to restore file permissions for temporary directories/files, so that they can be successfully removed after each test no matter what.

Note: we should consider applying this fix only for tests that use the local filesystem, as I have a feeling that other filesystems like jimfs (which we intend to support) might not support file permissions.

This issue is a follow-up to #348 | #491.

Relevant JUnit 5 issues:

• Make @TempDir restore mint permissions before closing context to avoid AccessDeniedException junit-team/junit5#2609