feat: add support for tcp endpoints in haproxy plugin

[jsnjack]

Required for all PRs

• Updated associated README.md.
• Wrote appropriate unit tests.
• Pull request title or commits are in conventional commit format

resolves #12672

• Added support for tcp endpoints in haproxy input plugin. For example, if haproxy is configured to expose stats endpoint with stats socket ipv4@127.0.0.1:9999 level admin, the plugin will be able to communicate with it with servers = ["tcp://127.0.0.1:9999"] configuration

[powersj]

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[powersj]

Thanks for taking the time to put up a PR. I have one small nit and a doc change that I'd like to see. Feel free to wordsmith or update that as you see fit.

Thanks!

[telegraf-tiger]

Download PR build artifacts for linux_amd64.tar.gz, darwin_amd64.tar.gz, and windows_amd64.zip.
Downloads for additional architectures and packages are available below.

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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

[powersj]

Thanks for putting this up!

[srebhan]

Looks good to me. Thanks for your contribution @jsnjack!