Update NwbFile.m : Generate uuid if no identifier is given for file

[ehennestad]

Motivation

nwbinspector docs states that MatNWB will add a uuid to the NWBFiles identifier property.

This was actually not happening, but this PR fixes that. When creating an NWB file using NwbFile, if no identifier is given on construction, a uuid is assigned.

How to test the behavior?

Creating an NwbFile object without an identifier:

>> nwb = NwbFile();
>> nwb.identifier

ans =

    '67028a4f-f303-4785-9330-63d31f894ce5'

Creating an NwbFile object with a custom identifier:

>> nwb = NwbFile('identifier', 'some_id');
>> nwb.identifier

ans =

    'some_id'

Checklist

• Have you ensured the PR description clearly describes the problem and solutions?
• Have you checked to ensure that there aren't other open or previously closed Pull Requests for the same change?
• If this PR fixes an issue, is the first line of the PR description fix #XX where XX is the issue number?

[Copilot]

Pull request overview

Fixes NwbFile construction so that an identifier is automatically assigned when omitted, aligning MatNWB behavior with the NWBInspector “best practice” guidance for NWBFile.identifier.

Changes:

• Adds automatic UUID assignment to identifier during NwbFile construction.
• Passes the generated identifier through to the underlying types.core.NWBFile constructor via name/value pairs.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.31%. Comparing base (6f4e97a) to head (52e9edb).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #839   +/-   ##
=======================================
  Coverage   95.31%   95.31%           
=======================================
  Files         219      219           
  Lines        7647     7648    +1     
=======================================
+ Hits         7289     7290    +1     
  Misses        358      358           

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