feat: add optional baseUrl and userAgent to Resend constructor#839

xiaoyu2er wants to merge 4 commits intoresend:canaryresend/resend-node:canaryfrom

xiaoyu2er:feat/resend-options-baseurl-useragentxiaoyu2er/resend-node:feat/resend-options-baseurl-useragentCopy head branch name to clipboard