[diag] count the number of packets that are sent succeed and failed (#11108)

When using the `diag frame -c xxxx` command to enable the CSMA-CA when
transmitting the frame, the command `diag send` won't output any message
the CCA failure happens. It is difficult for users to know whether
the CSMA-CA is actually effective via diag commands.

This commit counts the number of packets that are sent succeed and failed,
outputs the transmision failure reason and do not re-transmit the frame
after it fails to send.

tests/scripts/expect/cli-diags.exp

@@ -68,7 +68,10 @@ sleep 2
 
 send "diag stats\n"
 expect "received packets: 0"
-expect "sent packets: 10"
+expect "sent success packets: 10"
+expect "sent error cca packets: 0"
+expect "sent error abort packets: 0"
+expect "sent error others packets: 0"
 expect "first received packet: rssi=0, lqi=0"
 expect "last received packet: rssi=0, lqi=0"
 expect_line "Done"
@@ -77,7 +80,10 @@ switch_node 1
 
 send "diag stats\n"
 expect "received packets: 10"
-expect "sent packets: 0"
+expect "sent success packets: 0"
+expect "sent error cca packets: 0"
+expect "sent error abort packets: 0"
+expect "sent error others packets: 0"
 expect "first received packet: rssi=-20, lqi=0"
 expect "last received packet: rssi=-20, lqi=0"
 expect_line "Done"
@@ -100,7 +106,10 @@ switch_node 1
 
 send "diag stats\n"
 expect -r {received packets: \d+}
-expect "sent packets: 0"
+expect "sent success packets: 0"
+expect "sent error cca packets: 0"
+expect "sent error abort packets: 0"
+expect "sent error others packets: 0"
 expect "first received packet: rssi=-20, lqi=0"
 expect "last received packet: rssi=-20, lqi=0"
 expect_line "Done"