feat(mqtt output): add ws:// and wss:// scheme support

[aitorhh]

Summary

Adds WebSocket (ws://) and WebSocket Secure (wss://) transport support to the MQTT output plugin.

Motivation

Many MQTT brokers (e.g., cloud-hosted or behind ingress controllers) only expose WebSocket endpoints. The MQTT input plugin (mqtt_consumer) already supports ws:// — this brings parity to the output.

Changes

• plugins/common/mqtt/mqtt_v3.go — preserve ws/wss schemes instead of overriding to tls
• plugins/common/mqtt/mqtt_v5.go — same fix for the v5 client
• plugins/outputs/mqtt/sample.conf — document ws:// and wss:// in the scheme list

Notes

The underlying paho.mqtt.golang library already supports WebSocket transport — this change simply passes the scheme through correctly.

Example config

[[outputs.mqtt]]
  servers = ["wss://broker.example.com:443"]
  topic = 'metrics/{{ .Tag "host" }}'
  username = "user"
  password = "${MQTT_TOKEN}"
  insecure_skip_verify = true
  keep_alive = 30
  data_format = "json"

[telegraf-tiger]

Thanks so much for the pull request!
🤝 ✒️ Just a reminder that the CLA has not yet been signed, and we'll need it before merging. Please sign the CLA when you get a chance, then post a comment here saying !signed-cla

[telegraf-tiger]

Download PR build artifacts for linux_amd64.tar.gz, darwin_arm64.tar.gz, and windows_amd64.zip.
Downloads for additional architectures and packages are available below.

☺️ This pull request doesn't significantly change the Telegraf binary size (less than 1%)

📦 Click here to get additional PR build artifacts

Artifact URLs

. DEB	. RPM	. TAR . GZ	. ZIP
amd64.deb	aarch64.rpm	darwin_amd64.tar.gz	windows_amd64.zip
arm64.deb	armel.rpm	darwin_arm64.tar.gz	windows_arm64.zip
armel.deb	armv6hl.rpm	freebsd_amd64.tar.gz	windows_i386.zip
armhf.deb	i386.rpm	freebsd_armv7.tar.gz
i386.deb	ppc64le.rpm	freebsd_i386.tar.gz
mips.deb	riscv64.rpm	linux_amd64.tar.gz
mipsel.deb	s390x.rpm	linux_arm64.tar.gz
ppc64el.deb	x86_64.rpm	linux_armel.tar.gz
riscv64.deb		linux_armhf.tar.gz
s390x.deb		linux_i386.tar.gz
		linux_mips.tar.gz
		linux_mipsel.tar.gz
		linux_ppc64le.tar.gz
		linux_riscv64.tar.gz
		linux_s390x.tar.gz