Add validation for namespace, metric and timestamp

[markkuhn]

Related to: #131

• Add dimension, metric and namespace validation aws-embedded-metrics-python#91
• Add dimension, metric and namespace validation aws-embedded-metrics-dotnet#37
• Add validation for dimension, metric, namespace and timestamp aws-embedded-metrics-java#119

Description of changes:
Adding validation for metrics and namespace since validating dimensions alone doesn't make sense.

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[markkuhn]

Update:

• The faker dependency currently used is deprecated/no longer maintained so I replaced it with @faker-js/faker.
• Updated TypeScript to 4.8.2
• Updated eslint to 8.23.0 and made some minor changes based on the new rules
• Since the min/max Metric values specified in the specs are outside the Number range, we will be validating against Number.MAX_SAFE_INTEGER and -Number.MAX_SAFE_INTEGER
• changed isNaN() to Number.isNaN()

Interesting read on what happened to faker and how the creator starting pushing malicious updates.