feat(processors.timestamp): Introduce timestamp processor

[powersj]

Summary

The following introduces a new timestamp processor. This allows a user to specify a field which contains a timestamp and convert it from one format to another. Traditionally telegraf assumes data has a single timestamp and uses that as the timestamp for the metric itself. However, if a user's data contains additional timestamps that they also wish to parse into a different format, there was no existing method for that.

The date processor exists today to take a metric's timestamp and add a tag or field with a subset of that timestamp. Trying to adapt that config to do both features made for a complex configuration that was not straightforward and error prone.

Checklist

• No AI generated code was used in this PR

Related issues

resolves #10524

[srebhan]

Thanks @powersj! Just a few comments/questions from my side...

[powersj]

@srebhan if you could take another look I would apprecaite it. Not sure about the destination timezone handling and if I could re-use anything we already have?

[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%)

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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

[srebhan]

Awesome! Thanks @powersj!