feat: port builder :report subcommands to golang

The bash :report implementations for the dockerfile, herokuish, lambda, nixpacks, pack, and railpack builders are replaced with a compiled golang binary that collects report keys in parallel and marshals json directly, avoiding the per-key subshell and jq forks that made the bash reports slow. The subcommands/report and root report trigger become symlinks to the compiled binary, while the non-report bash helpers each plugin still relies on are left in place.

plugins/builder-lambda/subcommands/report

@@ -1,6 +0,0 @@
-#!/usr/bin/env bash
-source "$PLUGIN_AVAILABLE_PATH/builder-lambda/internal-functions"
-set -eo pipefail
-[[ $DOKKU_TRACE ]] && set -x
-
-cmd-builder-lambda-report "$@"