Fixed diff file states getting incorrectly set

What does this MR do?

Fixes the diff file states getting used incorrectly. When the virtual scroller is enabled each diff file gets a re-used component so using the data property would mean that the state gets shared. With this IdState mixin, we can re-use the components and have their own state.

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

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Security

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