feat(processors.converter): Add support for base64 encoded IEEE floats

[vkrasnici]

Summary

When using Cisco Telemetry MDT (cisco_telemetry_mdt) Input Plugin in combination with OpenConfig power Yang model (openconfig-platform:components/component/power-supply) the data is received but the power values are Base64 Encoded IEEE 754 Float32.
The format received looks like below:

{"fields":{"data_json_content_state_openconfig-platform-psu:input-current":"QWAAAA==","data_json_timestamp":"1731938073759"},"name":"file","tags":{"host":"YJ4"},"timestamp":1732125250}
{"fields":{"data_json_content_state_openconfig-platform-psu:output-current":"QcAAAA==","data_json_timestamp":"1731938073763"},"name":"file","tags":{"host":"YJ4"},"timestamp":1732125250}
{"fields":{"data_json_content_state_openconfig-platform-psu:input-current":"QVAAAA==","data_json_timestamp":"1731938073766"},"name":"file","tags":{"host":"YJ4"},"timestamp":1732125250}
{"fields":{"data_json_content_state_openconfig-platform-psu:output-power":"RKeAAA==","data_json_timestamp":"1731938073773"},"name":"file","tags":{"host":"YJ4"},"timestamp":1732125250}

This makes the data unusable for metrics, as metrics should be represented by float/int (number). Using parser.json and parse_fields_base64 converts b64 to byte/str, but that's not enough to convert it to metrics, hence the motivation to add the converter support.

Checklist

• No AI generated code was used in this PR

Related issues

Closes #16213

[DStrand1]

Thanks for the PR! I have a preliminary comment about the linter failure on this PR

[vkrasnici]

@DStrand1 is there anything you want me to change?

[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.

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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]

Thanks @vkrasnici for your contribution!

[srebhan]

CI errors are unrelated.