Fix #5614: Handle UTF-8 BOM in EPW files

[wnykuang]

Summary

• Fix EpwFile cannot process epw file #5614
• Strip a leading UTF-8 byte order mark before parsing an EPW LOCATION header.
• Add a regression test proving BOM-prefixed EPW content remains loadable.

Root cause

EpwFile::parse passed the first line through unchanged, while parseLocation requires the first comma-delimited field to equal LOCATION. For UTF-8-with-BOM files, that field begins with the bytes EF BB BF, so a valid header was reported as missing its LOCATION specifier.

The fix only removes a UTF-8 BOM at the beginning of the first line. Existing validation remains unchanged, and this does not attempt to decode UTF-16 or UTF-32 files.

User impact

EPW files saved as UTF-8 with BOM, including the file attached to #5614, can now be processed normally.

Validation

• Added Filetypes.EpwFile_UTF8BOM and observed it fail before the implementation change and pass afterward.
• Ran all 25 Filetypes.EpwFile* tests successfully.
• Re-ran the original 2.5 MB EPW attachment from EpwFile cannot process epw file #5614 and confirmed the parsing failure no longer occurs.
• Ran git diff --check successfully.

Fixes #5614.

[jmarrec]

Ok. Not my prefered style of declaration, but it's valid and defensive (would work with a null byte in the middle too)

[jmarrec]

Ah shoot, since CI is failing due to BCL tests, I didn't notice that Windows x64 was failing the new test.

https://github.com/NatLabRockies/OpenStudio/actions/runs/29307997109/job/87338834472#step:23:9224

  [ RUN      ] Filetypes.EpwFile_UTF8BOM
  [openstudio.EpwFile] <1> Insufficient weather data on line 8769 of EPW file ''
  D:\a\OpenStudio\OpenStudio\OpenStudio\src\utilities\filetypes\test\EpwFile_GTest.cpp(60): error: Value of: epwFile
    Actual: false
  Expected: true

@wnykuang

[wnykuang]

@jmarrec thanks for bringing it up, let me try to reproduce and fix it.

[jmarrec]

I fixed it in #5633 already

[wnykuang]

I fixed it in #5633 already

Thanks let me close it