Add `UnstructuredData` and `UncategorisedData` concepts/properties

[coolharsh55]

1. Add property hasUnstructuredData to indicate data is "without a pref-defined data model or is not organised in a pre-defined manner" (source: Wikipedia). This is relevant to application of privacy/data protection regulations like GDPR, as unstructured data may contain PII/personal data. The range of the property would be dpv:Data, but to be more precise a new concept called UnstructuredData should be added as a subclass of dpv:Data.
2. Since unstructured only refers to the underlying modelling of data, the more precise relation hasUncategorisedData should be added to indicate data that has not been categorised according to some (legally) relevant category - such as for indicating whether it is PersonalData or NonPersonalData (or both). The concept UncategorisedData as a subclass of dpv:Data would be range of this.
3. The concepts relating to structure should be added to TECH extension as there may be additional related concepts (e.g. metadata) that we would want to add. The concepts relating to categorisation should be added to DPV alongside existing concepts as these are relevant for legal and organisational processes.
4. Whether the concepts StructuredData and CategorisedData are needed should be discussed (e.g. it is necessary to flag unstructured and uncategorised data, but is the inverse necessary?). These concepts might be helpful to indicate the data is not unstructured and not uncategorised.
5. The concept UncategorisedData would also be helpful for exploring the concept UnlabelledData to be added to TECH or AI extension.

Proposal with @brennanraj