TODO: Do not create LFN entries when unneeded

[henrygab]

Currently, the long file name (LFN) directory entries are always created.
This issue is to track the feature that avoids creating the LFN entries when not needed.
Conditions:

• The file name fits in 8.3 naming convention (e.g., The file name is equal to the generated SFN)
• Neither the SFN nor the LFN exist in the directory (e.g., no collision of names, likely does not need any change, but need to verify)

(putting TODO list into issues for easier tracking and referencing in pull requests)