Add data class tests

[Agaba-derrick]

ColorRuleTest: Unit Tests for ColorRule Class

This test suite covers various functionalities of the ColorRule class within the org.opendatakit.data package. The ColorRule class is responsible for defining rules for color-coding based on conditions.

Key Features:

• Initialization:

  • The tests initialize a ColorRule object with sample values.

• JSON Representation:

  • The testGetJsonRepresentation() method checks that the object can be correctly converted to a JSON-like structure.

• Getters and Setters:

  • Tests ensure that getters (testGetVal(), testGetForeground(), etc.) return the expected values, while setters update the values correctly.

• Equality:

  • Tests such as testEquals() and testNotEqualsDifferentId() validate object equality with and without IDs.

this fixes #512 and #507