ignore missing files when deleting TempDirectory

[panchenko]

I've got an exception when TempDirectory was deleting its contents because one of the files has been deleted at the same time by the process started from test.
I think such disappearing files should be ignored by TempDirectory.

java.nio.file.NoSuchFileException: /var/folders/5p/6vn1lg4d6x3b5rmct9nkn96w0000gn/T/junit1862350231264789347/logs/foo.pid
    at sun.nio.fs.UnixException.translateToIOException(UnixException.java:86)
    at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:102)
    at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:107)
    at sun.nio.fs.UnixFileAttributeViews$Basic.readAttributes(UnixFileAttributeViews.java:55)
    at sun.nio.fs.UnixFileSystemProvider.readAttributes(UnixFileSystemProvider.java:144)
    at java.nio.file.Files.readAttributes(Files.java:1737)
    at java.nio.file.FileTreeWalker.getAttributes(FileTreeWalker.java:219)
    at java.nio.file.FileTreeWalker.visit(FileTreeWalker.java:276)
    at java.nio.file.FileTreeWalker.next(FileTreeWalker.java:372)
    at java.nio.file.Files.walkFileTree(Files.java:2706)
    at java.nio.file.Files.walkFileTree(Files.java:2742)
    at org.junitpioneer.jupiter.TempDirectory$CloseablePath.deleteAllFilesAndDirectories(TempDirectory.java:275)
    at org.junitpioneer.jupiter.TempDirectory$CloseablePath.close(TempDirectory.java:267)
...

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[sbrannen]

Please note that the TempDirectory extension in JUnit Pioneer is effectively deprecated (see #136) and was moved to JUnit Jupiter in Jupiter 5.4.

Also, a similar bug was fixed in junit-team/junit5#1801.

Though, your proposed fixed adds a check on a per-file level. Perhaps you'd like to propose that particular fix for JUnit Jupiter?

[nipafx]

Since Pioneer's extension is not yet deprecated (and #136 makes it look like it may survive for the time being) I'm going to rebase and merge this.

[nipafx]

I wondered about this change and tried to write a test for it, but couldn't. In the end, I came up with the explanation the comment describes. Would be nice of somebody could sanity-check it.

[nipafx]

Could this be interesting for the Jupiter test superclass? It makes it easier to launch a bunch of tests methods if they have parameters. Nota bene: I also wondered whether Jupiter could be a little more lenient and select a test method by name only (i.e. ignoring parameter types) if there is only one method of that name.

[nipafx]

Proposed commit message:

TempDirectory ignores missing files when cleaning up

If a process under test deletes temporary files *while* the extension
is cleaning up after itself, the extension may throw an exception
because it tries to delete a no longer existing file. This is
unneccessary and easily fixed by using `Files.deleteIfExists`.

PR: #140