Support prefix date formatting for rolling log filenames

[DawnTreader]

Currently, the File sink with rollingInterval appends the date as a suffix to the log filename (e.g. edonexuscore20251130.log).

In some environments, we need the date/time as a prefix instead, to make log files easier to sort and scan (e.g. 2025-11-30 15-25-28 edonexuscore.log).

Right now, the only way to achieve this is to manually generate a timestamped filename and drop rollingInterval, which means losing automatic daily rotation.

Feature request: Add support for configurable filename formatting in the File sink, including the ability to place the rolling date before the base filename.

Example desired behavior:

text
2025-11-30 edonexuscore.log
2025-12-01 edonexuscore.log
or with time granularity:

text
2025-11-30 15-25-28 edonexuscore.log
This would allow us to keep both prefix‑style timestamps and Serilog’s rolling interval rotation.

Thanks for considering — this would make log management much more flexible for teams that prefer prefix‑based naming conventions.