Fix/delta display refactor

[samarthsinh2660]

Description

Refactors the LfxDeltaDisplay component to use a more flexible unit-based approach for durations, replacing the boolean isDuration flag with deltaUnit.

Changes

• LfxDeltaDisplay: Replaced isDuration prop with deltaUnit (of type FormatterUnits).
• Types: Updated DeltaDisplayProps to include deltaUnit and remove isDuration.
• Logic: Updated component logic to use deltaUnit when calling formatSecondsToDuration.
• Consumers: Updated MedianTimeToClose and MedianTimeToReview widgets to use the new delta-unit prop.
• Stories: Updated Storybook configuration for LfxDeltaDisplay to reflect prop changes.
• CI: Added pull-requests: write and statuses: write permissions to pr-title-lint.yml to resolve "Resource not accessible by integration" errors in CI.

Verification

• pnpm tsc-check passed.
• Verified that duration-based deltas are still formatted correctly in the widgets.

[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