File output plugin should support File Rollover

**Is your feature request related to a problem? Please describe.**
Current `File` output plugin doesn't have mechanism for File Rollover,
**Describe the solution you'd like**
* Would like to have Rollover mechanism based on,

1. Time.
2. File size.
* The naming convention should contain time stamp file was created.
* Though good to have, there should be housing keeping activity, to clear archived logs, May be we can ignore this. this can be managed by separate application/docker which could be better handled by K8s cron jobs,
* Log message should be complete, shouldn't be partial in case of file size based roll over.

**Additional context**

[Stackoverflow question](https://stackoverflow.com/questions/58498040/configure-fluent-bit-file-output-plugin-set-file-rollover/58577944#58577944)

The issue names the File output plugin but no source files, tests, or entry points. Start by locating that plugin and its existing tests, then review how output writes and buffering are handled. Done should cover time- and size-based rollover, timestamped filenames, and complete log messages without requiring housekeeping.

Written by the indexing model from the issue text.