fix: sanitize page titles and display names used as folder path segments in OneNote importer

[aaron-meyers]

OneNote import was not sanitizing page titles and section/group names when creating folders which could result in unexpected subfolder levels, names with leading or trailing whitespace etc.

Tested locally.

[aaron-meyers]

@tgrosinger any concerns with this change? I have some other improvement ideas for the OneNote importer in mind but wanted to get this small fix in before doing anything too drastic 😅

[tgrosinger]

Looks good to me overall, except I would prefer if we could avoid the assertions where possible. Perhaps add a fallback instead?

sanitizeFileName(notebook.displayName ?? 'Untitled Notebook')
sanitizeFileName(page.title ?? 'Untitled')
sanitizeFileName(sectionGroup.displayName ?? 'Untitled')

Thank you!

[aaron-meyers]

Done. The code appeared to be assuming these were non-empty/non-null already but added the fallback for good measure (this might actually fix a bug because I think it is possible for OneNote pages at least to have an empty title). I used || so that empty string falls back as well.