Fix/server api todo fixes

[samarthsinh2660]

Description

Refactors filter types in the server-side data layer to eliminate redundancy and improve maintainability.

Changes

• Type Inheritance: Updated all filter types in server/data/types.ts to inherit from DefaultFilter.
• Cleanup: Removed redundant fields (project, repos, startDate, endDate) from specialized filter types like ActiveContributorsFilter, MergeLeadTimeFilter, MedianTimeToCloseFilter, etc.
• TODO Resolution: Addressed the TODO note in server/data/types.ts regarding filter type refactoring.

Verification

• pnpm tsc-check passed in the frontend directory.
• Verified that all server-side API handlers still correctly type-check with the refactored filters.

[gaspergrom]

Hey, I will close this one as we are currently not yet opened for contributions (https://github.com/linuxfoundation/insights/blob/main/README.md) and there is no way for you to test your changes