Cover datasource_data_records with unit tests

[mawasile]

This pull request includes a number of changes related to the Power Platform provider and data records in the Power Platform. The most significant changes involve the addition of new data sources and modifications to existing data records.

Here are the most important changes grouped by theme:

Data Record Modifications:

• docs/resources/data_record.md: The parent_business_unit_id variable was removed and replaced with a call to powerplatform_data_records. This change was made in both the provider "powerplatform" block and the resource "powerplatform_data_record" "role" block. [1] [2] [3] [4]
• internal/powerplatform/services/data_record/api_data_record.go: Several functions were modified to use GetEntityDefinition instead of getEntityDefinition and to take environmentId as a parameter. Additionally, GetEntityRelationDefinitionInfo no longer returns primaryIdFieldName. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11]

New Data Sources:

• internal/powerplatform/provider.go: A new data source, data_record.NewDataRecordDataSource(), was added to the list of data sources.
• internal/powerplatform/provider_test.go: The new data source was also added to the test for data sources.
• examples/data-sources/powerplatform_data_records/data-source.tf: A new example file was created to demonstrate the use of the new data source.
• examples/data-sources/powerplatform_data_records/output.tf: This new file outputs the results of the data query from the new data source.

Documentation Updates:

• docs/resources/user.md: The description was updated to improve readability by adding line breaks between the links.