Preview `.rds` file contents in the Data Explorer from the file explorer

Clicking a CSV or parquet file in the file explorer opens its contents directly in the Data Explorer. Clicking an .rds file instead only offers to load the object into the R session (the opener added in #9204). There's no way to preview the contents of an .rds file without loading it into a session first.

Request: let the Data Explorer render the contents of an .rds file when it's selected in the file explorer, matching the CSV/parquet experience.

Context

The Data Explorer reads CSV/parquet via DuckDB, which doesn't support the RDS format (nor does Polars). Supporting a preview would likely require reading the file through another mechanism (e.g. the R session itself) before handing rows to the Data Explorer.

Related

• #9204 - added the current .rds opener that loads the object into a variable (the existing behavior)
• #14414 - proposal to import an already-previewed CSV/parquet/XLSX into R/Python (the reverse direction)

Source

Feedback discussion: https://github.com/posit-dev/positron/discussions/14988

Start with the existing .rds opener added in #9204 and compare it with the CSV/parquet path into the Data Explorer. Determine how an R session could provide preview rows, then verify that selecting an .rds file renders its contents in the Data Explorer without relying on the existing load-into-variable behavior.