SPINEL_PROP_THREAD_MGMT_SET_PENDING_DATASET_TLVS value

Send MGMT_SET Thread Pending Operational Dataset (in TLV format). Format: `D` - Write only This is write-only property. When written, it triggers a MGMT_PENDING_SET meshcop command to be sent to leader with the given Dataset. When setting this property, the spinel frame response will be: 1. A `LAST_STATUS` with the status of the transmission of MGMT_PENDING_SET command if it fails. 2. A `SPINEL_PROP_THREAD_MGMT_SET_PENDING_DATASET_TLVS` with no content. On response reception or timeout, another notification will be sent to the host: A `SPINEL_PROP_THREAD_MGMT_SET_PENDING_DATASET_TLVS` with a spinel_status_t indicating the result of MGMT_SET_PENDING. On write, any unknown/unsupported TLVs must be ignored.