feat(metrics): ability to set custom timestamp with setTimestamp for metrics

[arnabrahman]

Summary

By default, the current timestamp is set while creating metrics. This PR provides an opportunity to provide custom timestamp with metrics

Changes

• Followed the Python implementation of the same feature for feature parity
• Create setTimestamp function to set the timestamp
• Validate the timestamp, if not a valid timestamp then log a warning
• Set the timestamp, if not a valid value set this to Zero for Cloudwatch to skip
• Write unit tests for the function, had to slightly change the date mock to test the new feature
• Add a section for the feature inside the doc

Issue number: #3153

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[dreamorosi]

Thank you for the PR @arnabrahman, looking good.

I've left a couple minor comments and a question

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
27.1% Duplication on New Code

See analysis details on SonarQube Cloud

[dreamorosi]

Hey @arnabrahman, just dropping this issue here (#3302) in case you're looking for something else to work on.

It's in the same area as this one and should be fairly simple. If not interested, feel free to chose another (if any)