feat: Add CopilotUsageChecker class for data analysis

[DevOps-zhuang]

The code changes include adding a new file CopilotUsageChecker.ts which contains the implementation of the CopilotUsageChecker class. This class is responsible for performing various checks on the data, such as checking for missing dates, empty breakdowns, and zero activity days. The class also provides a method runChecks() to run all the checks and return the results.

[DevOps-zhuang]

Data quality of the usage data #54

[karpikpl]

Hey @DevOps-zhuang - do you know what's the reason dates are missing? is that an API issue or by design? can you update your PR with latest main and change the warning so it doesn't go away after few seconds? :)

[karpikpl]

I think that was already included through a different PR