chore: avoid non-API calls to Rf_findVar(), Rf_findVarInFrame(), and R_UnboundValue#2604

krlmlr merged 6 commits intomainigraph/rigraph:mainfrom

copilot/avoid-non-api-calls-to-rf-findvarigraph/rigraph:copilot/avoid-non-api-calls-to-rf-findvarCopy head branch name to clipboard