restore() gains retry argument for non-interactive recovery

[kevinushey]

Adds a retry argument to renv::restore(), addressing the non-interactive gap in #1893.

The retry-with-latest recovery added in #1893 (renv 1.2.1) was interactive-only: renv_restore_recover() calls ask(), which returns the default (FALSE) in non-interactive sessions, so the retry was silently skipped in CI, pre-commit, Rscript, etc. This was flagged by @froggleston.

Behavior

retry is tri-state, so the existing interactive prompt is preserved:

• retry = NULL (default) -- prompt if interactive, leave failures unresolved otherwise (unchanged).
• retry = TRUE -- retry failed packages with their latest available versions without prompting (the CI case).
• retry = FALSE -- skip recovery entirely.

When retrying without a prompt, renv prints a short "Retrying with the latest available versions of: ..." line. The detailed per-package failure summary is already emitted by renv_graph_install_errors() beforehand.

Notes

• This applies to the graph installer path only; the pak-delegated restore returns early and never had this recovery, so retry is a no-op there (matches the pre-existing limitation).
• It retries with latest-available versions, not a minimal incremental version bump. The latter is a larger feature, best handled separately.

Testing

devtools::test(filter = "restore") -> FAIL 0, PASS 93. Added a test asserting retry = FALSE skips recovery and retry = TRUE installs the latest version.