tool/{node,yarn}: update node and yarn tools

Syncing these up with what we've got in corp.

Updates tailscale/corp#13775

Signed-off-by: Sonia Appasamy <sonia@tailscale.com>

tool/node

@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+# Run a command with our local node install, rather than any globally installed
+# instance.
+
+set -euo pipefail
+
+if [[ "${CI:-}" == "true" ]]; then
+    set -x
+fi
+
+(
+    if [[ "${CI:-}" == "true" ]]; then
+        set -x
+    fi
+
+    repo_root="${BASH_SOURCE%/*}/../"
+    cd "$repo_root"
+
+    cachedir="$HOME/.cache/tailscale-node"
+    tarball="${cachedir}.tar.gz"
+
+    read -r want_rev < "$(dirname "$0")/node.rev"
+
+    got_rev=""
+    if [[ -x "${cachedir}/bin/node" ]]; then
+        got_rev=$("${cachedir}/bin/node" --version)
+        got_rev="${got_rev#v}" # trim the leading 'v'
+    fi
+
+    if [[ "$want_rev" != "$got_rev" ]]; then
+        rm -rf "$cachedir" "$tarball"
+        if [[ -n "${IN_NIX_SHELL:-}" ]]; then
+            nix_node="$(which -a node | grep /nix/store | head -1)"
+            nix_node="${nix_node%/bin/node}"
+            nix_node_rev="${nix_node##*-}"
+            if [[ "$nix_node_rev" != "$want_rev" ]]; then
+                echo "Wrong node version in Nix, got $nix_node_rev want $want_rev" >&2
+		        exit 1
+            fi
+            ln -sf "$nix_node" "$cachedir"
+        else
+            # works for "linux" and "darwin"
+            OS=$(uname -s | tr A-Z a-z)
+            ARCH=$(uname -m)
+            if [ "$ARCH" = "x86_64" ]; then
+                ARCH="x64"
+            fi
+            if [ "$ARCH" = "aarch64" ]; then
+                ARCH="arm64"
+            fi
+            mkdir -p "$cachedir"
+            curl -f -L -o "$tarball" "https://nodejs.org/dist/v${want_rev}/node-v${want_rev}-${OS}-${ARCH}.tar.gz"
+            (cd "$cachedir" && tar --strip-components=1 -xf "$tarball")
+            rm -f "$tarball"
+        fi
+    fi
+)
+
+export PATH="$HOME/.cache/tailscale-node/bin:$PATH"
+exec "$HOME/.cache/tailscale-node/bin/node" "$@"