Fix objects merging in loadMore after refetch in usePaginationFragment

[DarynaAkhmedova]

The scope of this PR is to fix loadMore function from usePaginationFragment hook after we refetch data with different variables
that contain objects.

Problem
When we have an object as part of the default variables, for example filterBy: {property1: true} and the same object with extended params are passed to the refetch function like filterBy: {property1: true, property2: false}, we end up in the situation where previousVariables in useLoadMore hook is incorrectly combined.

In this case:

const previousVariables = {
    ...metadata.connection?.filterVariableDefaults,
    ...latestVariablesUsedByStandaloneRefetch,
    ...fragmentReference.__fragments,
}

metadata.connection?.filterVariableDefaults.filterBy = {property1: true}
latestVariablesUsedByStandaloneRefetch = {property1: true, property2: false}
fragmentReference.__fragments = {property1: true}

The end result will be missing second parameter from latestVariablesUsedByStandaloneRefetch
const previousVariables.filterBy = {property1: true}

To repro and test this scenario we added a new test case uses correct variable value in load next request when previous variable already contains an object that is different on refetch

Solution
To fix the problem we used merge function of lodash library to recursively merge objects at all levels. In this case we will ensures that every layer of nested properties is combined.

[DarynaAkhmedova]

@alloy, @freiksenet, can you please have a look at this PR? :)