Refactor SeriesFile into an Interface

__Proposal:__
Refactor series file into an interface

__Current behavior:__
The current series file management we are using is a fixed type, rather than an interface.
If we can refactor it, we can implement our own custom series file.
I don't know why `Engine` and `Index` are interfaces but ignore `SeriesFile`. Even if we have a new TSDB engine, but we have to rely on this fixed `SeriesFile`

__Desired behavior:__
refactor series file into an interface

__Alternatives considered:__

__Use case:__
- customize series management, such as using some central service

Start by locating SeriesFile and comparing how Engine and Index are represented as interfaces. Review the existing series-file management and its consumers; done means custom series-file implementations can be substituted without breaking current behavior.

Written by the indexing model from the issue text.