feat: make pubsub topic configurable

[MikeDombo]

Issue #, if available:
Closes #10

Description of changes:

Resolves #10 by making the pubsub topic configurable just like the MQTT topic is configurable.

Why is this change necessary:

How was this change tested:

Any additional information or context required to review the change:

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[github-actions]

Unit Tests Coverage Report

File	Coverage	Lines	Branches
All files	98%	99%	97%	✅
com.aws.greengrass.telemetry.nucleus.emitter.publisher.PubSubPublisher	100%	100%	0%	✅
com.aws.greengrass.telemetry.nucleus.emitter.publisher.MqttPublisher	100%	100%	100%	✅
com.aws.greengrass.telemetry.nucleus.emitter.metrics.PeriodicMetricsEmitter	100%	100%	0%	✅
com.aws.greengrass.telemetry.nucleus.emitter.metrics.SystemMetricsEmitter	100%	100%	0%	✅
com.aws.greengrass.telemetry.nucleus.emitter.metrics.KernelMetricsEmitter	100%	100%	100%	✅
com.aws.greengrass.telemetry.nucleus.emitter.NucleusEmitter	98%	100%	97%	✅
com.aws.greengrass.telemetry.nucleus.emitter.NucleusEmitterConfiguration	95%	95%	96%	✅
com.aws.greengrass.telemetry.nucleus.emitter.Constants	0%	0%	0%	❌

Minimum allowed coverage is 90%

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