Add randomPlaceholderImage API

[try-catch-stack]

Description

Used https://picsum.photos/ api to generate random placeholder image with the given height and width by the user

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Checklist

• [X] API used in this PR was not used in just-calling-random-api before.
• [X] API used in this PR is Public or I have permission to use it.
• [X] My contribution is working.
• [X] My contribution doesn't expose any API keys.
• [X] My changes don't generate any new warnings.
• [X] My changes don't affect any work done by other developers.

[vedangj044]

Thanks for the PR