Prefer null values over empty strings

[jrasm91]

The Immich API and database should store null instead of empty strings.

Columns where this is happening:

• album.description (feat: store null instead of empty string for album.description #30123)
• asset_exif.description (fix(server): store null instead of empty string for asset_exif description #30069)
• person.name (fix(server): store null instead of empty string for person name #29702)
• person.thumbnailPath (fix(server): store null instead of empty string for person thumbnailPath #30070)
• session.deviceType (fix(server): store null instead of empty string for session deviceType and deviceOS #30048)
• session.deviceOS (fix(server): store null instead of empty string for session deviceType and deviceOS #30048)
• user.password (fix(server): store null instead of empty string for user password #30223)
• user.profileImagePath (fix(server): store null instead of empty string for user profileImagePath #30141)
• user.oauthId (fix(server): store null instead of empty string for user oauthId #30157)
• user.name (fix(server): store null instead of empty string for user name #30106)

[sujalgawas]

Can you assign this issue to me?

[jrasm91]

Feel free to open a PR. No need for it to be assigned.