Support TACACS Accounting

[CLUDev]

- What I did
Add TACAS Accounting configuration using pam_ as an enhancement

- How I did it
Add "common-session-sonic.j2"
Add accounting in "hostcfgd"

- How to verify it
== check aaa accounting command ==
root@SONiC-Inventec-d7054:# config aaa accounting session tacacs+
root@SONiC-Inventec-d7054:# config aaa authentication login local tacacs+
root@SONiC-Inventec-d7054:# config tacacs add 192.168.3.50
root@SONiC-Inventec-d7054:# config tacacs passkey admin

root@SONiC-Inventec-d7054:# cat /etc/pam.d/common-session-sonic

/etc/pam.d/common-session - session-related modules common to all services

This file is included from other service-specific PAM config files,
and should contain a list of modules that define tasks to be performed
at the start and end of sessions of any kind (both interactive and
non-interactive).
As of pam 1.0.1-6, this file is managed by pam-auth-update by default.
To take advantage of this, it is recommended that you configure any
local modules either before or after the default block, and use
pam-auth-update to manage selection of other modules. See
pam-auth-update(8) for details.

Here are the per-package modules (the "Primary" block)
session [success=done new_authtok_reqd=done default=ignore] pam_tacplus.so server=192.168.3.50:49 secret=admin service=shell
session [default=1] pam_permit.so

Here's the fallback if no module succeeds
session requisite pam_deny.so

prime the stack with a positive return value if there isn't one already;
this avoids us returning an error just because nothing sets a success code
since the modules above will each just jump around
session required pam_permit.so

and here are more per-package modules (the "Additional" block)
session required pam_unix.so

== check /etc/sonic/config_db.json ==

root@SONiC-Inventec-d7054:# config save
root@SONiC-Inventec-d7054:# cat /etc/sonic/config_db.json

"AAA": {
    "accounting": {
        "session": "tacacs+"
    },
    "authentication": {
        "login": "local,tacacs+"
    }
},

- Description for the changelog

Accounting is one of the services provided by AAA (Authentication, authorization, accouting) that logs session statistics and usage information, it is also used for authorization control, billing, trned analysis, resource utilization, and capacity planning activities.

- A picture of a cute animal (not mandatory but encouraged)

[msftclas]

All CLA requirements met.

[lguohan]

can you format your message? also we need a description of this feature, what is tacacs accounting.

[renukamanavalan]

Tabbing does not look right. Should be at the same level as 'key == authentication"

[CLUDev]

Thanks for the review.
Indentation level has been corrected, please check again.
Thank you!

[CLUDev]

can you format your message? also we need a description of this feature, what is tacacs accounting.

sure thing, please check the modification.
Thanks!

[CLUDev]

Hi @renukamanavalan Would you please review the pull request again? Thank you!