convert check-yarn to bash and move to repo root

dotcom-rendering/makefile

@@ -183,8 +183,8 @@ validate-build: # private
 
 check-env: # private
 	$(call log, "checking environment")
-	@ cd .. && scripts/env/check-node
-	@node scripts/env/check-yarn.js
+	@cd .. && scripts/env/check-node
+	@cd .. && scripts/env/check-yarn
 
 clear: # private
 	@clear

scripts/env/check-yarn

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+
+# Check that yarn is available. If not, ask the user to run `corepack enable`
+# which will provide it. Note that any yarn@>1 will do, since it will defer to
+# the copy in that lives in .yarn/releases (which is the version we want to
+# use).
+
+in_terminal() { test -t 1; }
+
+strip_colors() {
+    local text="$1"
+    printf "$text" | sed -e $'s/\x1b\[[0-9;]*m//g'
+}
+
+log_with_color() {
+    local text="$1"
+
+    # Check if output is a terminal and supports color
+    if in_terminal && [[ $(tput colors) -ge 8 ]]; then
+        # Terminal supports color, print the text as it is
+        echo -e "$text"
+    else
+        # Terminal does not support color, strip color codes and print
+        echo "$(strip_colors "$text")"
+    fi
+}
+
+blue='\033[0;34m'
+red='\033[0;31m'
+dim='\033[2m'
+reset='\033[0m'
+
+if ! command -v yarn &> /dev/null; then
+	log_with_color "${red}Could not find yarn. Please run 'corepack enable'.${reset}"
+	exit 1
+fi
+
+log_with_color "${dim}Using yarn ${blue}$(yarn -v)${reset}"