Filter out duplicate estimates

[mrfelton]

This addresses a bug in which duplicate entries were not always filtered out.

This pull request involves changes to the DataProviderManager class in src/lib/DataProviderManager.ts and the MockProvider3 class in test/DataProviderManager-merge.test.ts. The changes primarily aim to refine the logic for adding estimates and expand the test data for the MockProvider3 class.

Here are the key changes:

Changes to DataProviderManager class:

• src/lib/DataProviderManager.ts: The logic for adding estimates has been simplified. The condition for adding an estimate now only checks if the current estimate is lower than the minimum of all existing estimates. The check for the absence of mergedEstimates[key] and the presence of estimates[key] has been removed. This change streamlines the logic and potentially improves the efficiency of the function.

Changes to MockProvider3 class:

• test/DataProviderManager-merge.test.ts: Additional test data has been added to the MockProvider3 class. Specifically, data points with keys "6" and "7" have been added to the getAllData method. This expanded test data can provide a more comprehensive evaluation of the DataProviderManager's functionality. [1] [2]