google-apis-core 1.0 (Faraday): download_dest receives gzip-compressed bytes instead of decompressed content

## Environment details

- **Ruby version:** 3.3.9
- **google-apis-core version:** 1.0.2
- **google-apis-drive_v3 version:** 0.79.0
- **faraday version:** 2.13+
- **OS:** Linux (Docker, also reproduced on macOS)

## Summary

After upgrading from `google-apis-core` 0.18.0 (httpclient) to 1.0.2 (faraday), binary file downloads via `download_dest` receive **raw gzip-compressed bytes** instead of the decompressed file content. The old httpclient backend handled this transparently via `transparent_gzip_decompression`.

## Steps to reproduce

\`\`\`ruby
require "google/apis/drive_v3"
require "stringio"

client = Google::Apis::DriveV3::DriveService.new
client.authorization = Google::Auth.get_application_default(["https://www.googleapis.com/auth/drive"])

# Download a binary file (e.g., .xlsx) from Google Drive
io = client.get_file("SOME_FILE_ID", download_dest: StringIO.new)
io.rewind
bytes = io.string

puts bytes.encoding #=> UTF-8
puts bytes[0..3].unpack1('H*') #=> "1f8b0800" (gzip magic number)
# Expected: "504b0304" (ZIP/XLSX magic number)
\`\`\`

## Expected behavior

`download_dest` should receive the **decompressed** file content — the actual XLSX/ZIP binary data with magic bytes `PK\x03\x04` (`504b0304`).

This was the behavior with `google-apis-core` 0.18.0 using httpclient, which had `transparent_gzip_decompression` enabled by default.

## Actual behavior

`download_dest` receives **raw gzip-compressed bytes** (magic bytes `\x1F\x8B` / `1f8b0800`). The content is not decompressed before being written to the IO/file.

This breaks any downstream code that expects the actual file content (e.g., parsing XLSX files with `rubyzip` or `roo`):

```
Zip::Error: Zip end of central directory signature not found
```

## Additional context

- **Affects all `download_dest` targets:** StringIO, Tempfile (binmode), and file path strings all receive gzip-compressed content.
- **Does not affect `export_file`:** Text exports (CSV, etc.) via `export_file` work correctly.
- **The `transparent_gzip_decompression` option was deprecated** in the Faraday migration (PR #23524), but no equivalent decompression was added for `download_dest`.
- **Workaround:** Pin `google-apis-core` to `< 1.0` to continue using the httpclient backend.

## Versions

| Gem | Working | Broken |
|---|---|---|
| `google-apis-core` | 0.18.0 (httpclient) | 1.0.2 (faraday) |
| `google-apis-drive_v3` | 0.66.0 | 0.79.0 |

Related: PR #23524 (httpclient → faraday migration)