otRadioFrame::::::mIsHeaderUpdated field

Indicates whether frame counter and CSL IEs are properly updated in the header. If the platform layer does not provide `OT_RADIO_CAPS_TRANSMIT_SEC` capability, it can ignore this flag. If the platform provides `OT_RADIO_CAPS_TRANSMIT_SEC` capability, then platform is expected to handle tx security processing and assignment of frame counter. In this case the following behavior is expected: When `mIsHeaderUpdated` is set, it indicates that OpenThread core has already set the frame counter and CSL IEs (if security is enabled) in the prepared frame. The counter is ensured to match the counter value from the previous attempts of the same frame. The platform should not assign or change the frame counter (but may still need to perform security processing depending on `mIsSecurityProcessed` flag). If `mIsHeaderUpdated` is not set, then the frame counter and key CSL IE not set in the frame by OpenThread core and it is the responsibility of the radio platform to assign them. The platform must update the frame header (assign counter and CSL IE values) before sending the frame over the air, however if the the transmission gets aborted and the frame is never sent over the air (e.g., channel access error) the platform may choose to not update the header. If the platform updates the header, it must also set this flag before passing the frame back from the `otPlatRadioTxDone()` callback.