add a `wait-ready` command for tapd and litd

[ZZiigguurraatt]

We need an equivalent of wait-ready for tapd and litd.

For example, as it is right now, we can try to upload a tapd macaroon to kubernetes secrets and when it does not exist, it seems lndinit just hangs because of #68 .

[djkazic]

Just updating this issue for better context; this is due to the init script having set -e. When lndinit returns a non-zero exit code, the entire init script exits.

Here's a potential fix for that by setting +e, retrying within the init script, then resetting -e:

            echo "[STARTUP] Uploading TAPRPC secrets to namespace: ${NS}"
            max_retries=5
            retry_delay=5
            attempt=1
            success=false

            # Temporarily disable 'exit on error' so retries can run even if lndinit fails.
            set +e
            while [ $attempt -le $max_retries ]; do
              echo "[INFO] Attempt ${attempt}/${max_retries} to upload TAPRPC secrets..."

              lndinit -v store-secret \
                --batch \
                --overwrite \
                --target=k8s \
                {{- if .Values.legacySecretEncoding }}
                --k8s.base64 \
                {{- end }}
                --k8s.namespace="${NS}" \
                --k8s.secret-name="${TAPRPC_SECRETS_NAME}" \
                "${TAP_DIR}"/*.macaroon
              rc=$?

              if [ $rc -eq 0 ]; then
                echo "[INFO] TAPRPC secrets successfully uploaded on attempt ${attempt}."
                success=true
                break
              elif [ $rc -eq 129 ]; then
                echo "[WARN] Input missing (macaroon files not found) on attempt ${attempt}."
              else
                echo "[ERROR] lndinit failed with exit code ${rc} on attempt ${attempt}."
              fi

              echo "[INFO] Retrying in ${retry_delay}s..."
              sleep $retry_delay
              attempt=$((attempt + 1))
            done
            # Re-enable 'exit on error'
            set -e

            if [ "$success" = false ]; then
              echo "[ERROR] Failed to upload TAPRPC secrets after ${max_retries} attempts."
              exit $rc
            fi

            echo "[STARTUP] Finished uploading TAPRPC secrets to namespace: ${NS}"