Add smallstep_device_collection_account resource (#25)

docs/data-sources/collection.md

docs/resources/collection.md

internal/provider/account/resource_test.go

internal/provider/collection/data_source.go

internal/provider/collection/model.go

internal/provider/collection/resource.go

internal/provider/collection/resource_test.go

internal/provider/device_collection_account/data_source.go

...al/provider/device_collection_account/data_source_test.go

internal/provider/device_collection_account/model.go

internal/provider/device_collection_account/resource.go

internal/provider/device_collection_account/resource_test.go

internal/provider/provider.go

internal/provider/utils/testutils.go

internal/provider/workload/data_source.go

internal/provider/workload/model.go

internal/provider/workload/models.go

internal/provider/workload/resource.go