[show][config] Add new snmp commands

[tsvanduyn]

- What I did
I created these new show commands:

show runningconfiguration snmp
show runningconfiguration snmp contact
show runningconfiguration snmp location
show runningconfiguration snmp community
show runningconfiguration snmp user

show runningconfiguration snmp contact --json
show runningconfiguration snmp location --json
show runningconfiguration snmp community --json
show runningconfiguration snmp user --json

These commands will check in the REDIS ConfigDB and get the information.

- How I did it
I created a standard snmp schema that was approved here:
sonic-net/SONiC#731

I also moved from using only the snmp.yml file to using the ConfigDB for the device.
sonic-net/sonic-buildimage#6205

Jinja template update:
sonic-net/sonic-buildimage#6134

This way the REDIS ConfigDB will be the source of truth but we can still use the snmp.yml file.

Since it is setup whenever the snmp docker container is restarted to pull this info into the ConfigDB we are able to use the data in the configdb for the show commands.
- How to verify it
You can run the show commands:

show runningconfiguration snmp
show runningconfiguration snmp contact
show runningconfiguration snmp location
show runningconfiguration snmp community
show runningconfiguration snmp user

show runningconfiguration snmp contact --json
show runningconfiguration snmp location --json
show runningconfiguration snmp community --json
show runningconfiguration snmp user --json

and compare the output to what is in the REDIS ConfigDB.

admin@switch1:~$ redis-cli -n 4 keys "*" | grep -i snmp 
SNMP_USER|travis
SNMP_COMMUNITY|Joe
FEATURE|snmp
SNMP_COMMUNITY|public
SNMP|CONTACT
SNMP|LOCATION
SNMP_COMMUNITY|Travis
admin@switch1:~$ redis-cli -n 4 hgetall "SNMP_USER|travis"
 1) "SNMP_USER_ENCRYPTION_TYPE"
 2) "AES"
 3) "SNMP_USER_AUTH_TYPE"
 4) "SHA"
 5) "SNMP_USER_ENCRYPTION_PASSWORD"
 6) "TravEncryptPass"
 7) "SNMP_USER_AUTH_PASSWORD"
 8) "TravAuthPass"
 9) "SNMP_USER_TYPE"
10) "Priv"
11) "SNMP_USER_PERMISSION"
12) "RO"
admin@switch1:~$ redis-cli -n 4 hgetall "SNMP_COMMUNITY|Joe"
1) "TYPE"
2) "RO"
admin@switch1:~$ redis-cli -n 4 hgetall "SNMP|CONTACT"
1) "travis"
2) "travis@contoso.com"
admin@switch1:~$ redis-cli -n 4 hgetall "SNMP|LOCATION"
1) "Location"
2) "Palm Springs"
admin@switch1:~$

- Previous command output (if the output of a command-line utility has changed)
N/A
- New command output (if the output of a command-line utility has changed)

admin@switch1:~$ show run snmp
Location
------------
Palm Springs


SNMP_CONTACT    SNMP_CONTACT_EMAIL
--------------  --------------------
travis          travis@contoso.com


Community String    Community Type
------------------  ----------------
Joe                 RO
public              RO
Travis              RO


User    Type    Auth Type    Auth Password    Encryption Type    Encryption Password
------  ------  -----------  ---------------  -----------------  ---------------------
travis  Priv    SHA          TravAuthPass     AES                TravEncryptPass
admin@switch1:~$ show run snmp location 
Location
------------
Palm Springs
admin@switch1:~$ show run snmp contact
Contact    Contact Email
---------  ------------------
travis     travis@contoso.com
admin@switch1:~$ show run snmp community
Community String    Community Type
------------------  ----------------
Joe                 RO
public              RO
Travis              RO
admin@switch1:~$ show run snmp server
agentAddress udp:161
agentAddress udp6:161
admin@switch1:~$ show run snmp user
User    Type    Auth Type    Auth Password    Encryption Type    Encryption Password
------  ------  -----------  ---------------  -----------------  ---------------------
travis  Priv    SHA          TravAuthPass     AES                TravEncryptPass
admin@switch1:~$ show run snmp location --json
{'Location': 'Palm Springs'}
admin@switch1:~$ show run snmp contact --json
{'travis': 'travis@contoso.com'}
admin@switch1:~$ show run snmp community --json
{'Joe': {'TYPE': 'RO'}, 'public': {'TYPE': 'RO'}, 'Travis': {'TYPE': 'RO'}}
admin@switch1:~$ show run snmp user --json
{'travis': {'SNMP_USER_ENCRYPTION_TYPE': 'AES', 'SNMP_USER_AUTH_TYPE': 'SHA', 'SNMP_USER_ENCRYPTION_PASSWORD': 'TravEncryptPass', 'SNMP_USER_AUTH_PASSWORD': 'TravAuthPass', 'SNMP_USER_TYPE': 'Priv', 'SNMP_USER_PERMISSION': 'RO'}}
admin@switch1:~$

[SuvarnaMeenakshi]

As comments.