[FL-1955] CLI RPC (#781)

- RPC: added CLI command to start session - all input bytes goes into RPC, all RPC output goes into VCP
- RPC: added command to close session (actually it only notifies transport layer)
- RPC: added recursive rmdir
- RPC: hard-coded listing for root directory (any, ext, int)
- Fixed CLI leak
- Fixed furi_record_delete leak
- Unit tests: repaired
- Unit tests: corrected output - remove excess, change dots with progress spinner
- Unit tests: added leak check
- Unit tests: SD mount check before start

Co-authored-by: Aleksandr Kutuzov <alleteam@gmail.com>

firmware/targets/f6/furi-hal/furi-hal-vcp.c

@@ -157,3 +157,8 @@ static void vcp_on_cdc_rx() {
 static void vcp_on_cdc_tx_complete() {
     osSemaphoreRelease(furi_hal_vcp->tx_semaphore);
 }
+
+bool furi_hal_vcp_is_connected(void) {
+    return furi_hal_vcp->connected;
+}
+