Loosen prefix restrictions in FS

[jamoore]

See comment ​https://github.com/openmicroscopy/openmicroscopy/commit/24c54949b82b82d45031763159ff3c9b4f4baadc#commitcomment-2942579

Raised by Andreas, since creating a file with a period was disallowed:

ValidationException: exception ::omero::ValidationException
{
    serverStackTrace =
    serverExceptionClass =
    message = Path contains illegal components
}

[mtbcarroll]

Will remove "." prefix restriction but in the usual case clients should use ClientFilePathTransformer.getFsFileFromClientFile to prevent such validation errors.

[jamoore]

Mark: would getFsFileFromClientFile silently change that value or throw an exception?

[mtbcarroll]

It would provide an adjusted string that should validate okay, probably it would prefix it with an underscore or something: the idea is that the client supplies a locally constructed File instance that may be awkwardly named and gets back an FsFile instance that validates okay (because it directly corresponds to something the server file system should support). (The toString() of that instance can be supplied for importing or whatever.)

I do agree with removing the "." prefix restriction, though.

[mtbcarroll]

Fixed by ​https://github.com/openmicroscopy/openmicroscopy/pull/989