* [saidump]

•	Saidump for DNX-SAI sonic-net/sonic-buildimage#13561

Solution and modification:
To use the redis-db SAVE option to save the snapshot of DB each time and recover later, instead of looping through each entry in the table and saving it.

(1) Updated sonic-buildimage/build_debian.sh, to install Python library rdbtools into the host.
(2) Updated sonic-buildimage/src/sonic-sairedis/saidump/saidump.cpp, add a new option -r, which updates the rdbtools's output-JSON files' format.
(3) Add a new script file: files/scripts/saidump.sh, to do the below steps
  For each ASIC0, such as ASIC0,

  1. Save the Redis data.
  sudo sonic-db-cli -n asic$1 SAVE > /dev/null

  2. Move dump files to /var/run/redisX/
  docker exec database$1 sh -c "mv /var/lib/redis/dump.rdb /var/run/redis$1/"

  3. Run rdb command to convert the dump files into JSON files
  sudo python /usr/local/bin/rdb --command json  /var/run/redis$1/dump.rdb | sudo tee /var/run/redis$1/dump.json > /dev/null

  4. Run saidump -r to update the JSON files' format as same as the saidump before. Then we can get the saidump result in standard output.
  docker exec syncd$1 sh -c "saidump -r /var/run/redis$1/dump.json"

  5. clear
  sudo rm -f /var/run/redis$1/dump.rdb
  sudo rm -f /var/run/redis$1/dump.json

(4) Update sonic-buildimage/src/sonic-utilities/scripts/generate_dump, replace saidump with saidump.sh

scripts/generate_dump

@@ -874,11 +874,11 @@ save_redis() {
 save_saidump() {
     trap 'handle_error $? $LINENO' ERR
     if [[ ( "$NUM_ASICS" == 1 ) ]] ; then
-        save_cmd "docker exec syncd saidump" "saidump"
+        save_cmd "saidump.sh" "saidump"
     else
         for (( i=0; i<$NUM_ASICS; i++ ))
         do
-            save_cmd "docker exec syncd$i saidump" "saidump$i"
+            save_cmd "saidump.sh $i" "saidump$i"
         done
     fi
 }