feat: Support option set in DV object [DHIS2-18370]

[maikelarabori]

Adds a new object (OptionSetItem) to the Visualization object, so users can save the option set along with the option set items they wish to be saved as part of their Visualization. The aggregation type is also required as the items can be aggregated or disaggregated. It depends on the users' choice.

[gnespolino]

would be nice to have e2e test for this

[maikelarabori]

would be nice to have e2e test for this

We do not do analytics e2e for tests that persist data @gnespolino. In addition, this is related to a metadata endpoint (not analytics), which we also do not do analytics e2e as they are already tested through integration tests. The integration tests in this PR, for example, extend H2ControllerIntegrationTestBase, which will persist and retrieve the data as part of the test. So we are testing the entire flow for this change (saving, reading, and asserting the response related).

We are not adding any new test that depends on those legacy tests based on metadata JSON files.
Our integration tests can do the same in a cleaner way.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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