Adjust long filename character limit

[sjlevy]

Suggest adjusting character limits formulated in issue #275 to be based on file system path length instead of URL, and to comply with the Windows path limitation (effectively 247 characters)

See post here for more details: https://wordpress.org/support/topic/long-filename-issues/#post-9066322

[jaswrks]

Just adding a related article posted on HN this morning. https://eklitzke.org/path-max-is-tricky

[sjlevy]

Good point. Maybe instead of a hard-coded length there could be an option to specify a max length in the Comet Cache settings? That way each user could easily tailor it to their environment since there seem to be many factors.