Unify how various `FileSource`s are applying projections?

Related to https://github.com/apache/datafusion/pull/17076

_tl;dr: file sources are applying projections in various areas. My proposal is to centralize this into one area. This way, we can avoid passing `FileScanConfig` in various places`_

Hi, I'm curious about the circular relationship between `FileScanConfig` and `FileSource`. Specifically, how various file sources apply projection when creating a file opener.

When we create a file stream in `FileScanConfig`, we do the following: https://github.com/apache/datafusion/blob/173989cc2fb55c30cd174b520754812ea408e00b/datafusion/datasource/src/file_scan_config.rs#L507-L514

`FileScanConfig` has an inner field of `FileSource`, and a `FileSource` creates a file opener. In both of these steps, we pass in `FileScanConfig`, which feels a bit weird to me. (1. `with_projection(self)`, and 2. `create_file_opener(..., self, ...)`.

Looking through the various implementation of `with_projection`, we see some file sources do nothing other than do a deep clone:

`ParquetSource`
https://github.com/apache/datafusion/blob/173989cc2fb55c30cd174b520754812ea408e00b/datafusion/datasource-parquet/src/source.rs#L575-L577

`JsonSource`
https://github.com/apache/datafusion/blob/173989cc2fb55c30cd174b520754812ea408e00b/datafusion/datasource-json/src/source.rs#L135-L137

It's not that they don't need to project columns, but the actual projection for these file sources occur in `create_file_opener`, hence why we pass in the `FileScanConfig` again.

`ParquetSource`
https://github.com/apache/datafusion/blob/173989cc2fb55c30cd174b520754812ea408e00b/datafusion/datasource-parquet/src/source.rs#L461-L470

`JsonSource`
https://github.com/apache/datafusion/blob/173989cc2fb55c30cd174b520754812ea408e00b/datafusion/datasource-json/src/source.rs#L99-L114

For the other file sources, the projection occurs within `with_projection`:

`CsvSource`
https://github.com/apache/datafusion/blob/173989cc2fb55c30cd174b520754812ea408e00b/datafusion/datasource-csv/src/source.rs#L260-L264

`AvroSource`
https://github.com/apache/datafusion/blob/173989cc2fb55c30cd174b520754812ea408e00b/datafusion/datasource-avro/src/source.rs#L98-L102

It would be nice to unify this logic, and make the design/relationship between `FileSource` and `FileScanConfig` much simpler. One idea I had was to move the explicit projection into the `create_file_opener` impls, removing the need to call `.with_projection`. WIth https://github.com/apache/datafusion/pull/17076, we'd just directly call `file_source.create_file_opener`.

Start with datafusion/datasource/src/file_scan_config.rs and compare FileSource implementations in the Parquet, JSON, CSV, and Avro source files, focusing on with_projection and create_file_opener. Review the related pull request, then define a unified projection path that removes the inconsistent FileScanConfig relationship and verify the affected file sources still apply projections correctly.

Written by the indexing model from the issue text.