Fix vnet_route_check for active and inactive routes, add --all option

[mramezani95]

What I did

Added the options -a and --all to scripts/vnet_route_check.py. Both options are equivalent. If none of them is provided, then when finding the VNET routes that are in APP DB but not in ASIC DB, we will ignore routes in APP DB that are not active.
Mock tests in tests/test_vnet_route_check.py are added to test this behavior.

How I did it

If -a and --all are not provided, we first filter routes in APP DB to find active routes and then check which active routes are not in ASIC DB. The status of each route is retrieved from STATE DB.

How to verify it

You can verify the behavior by running mock tests in tests/test_vnet_route_check.py, or by manually running the vnet_route_check.py script on a DUT.

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)

N/A

[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[prsunny]

@mramezani95 , can you provide a sample output before and after this fix?

[prsunny]

@PrasadSamudrala, please review

[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[mramezani95]

@mramezani95 , can you provide a sample output before and after this fix?

The format of the output has not changed. This fix only affects which routes are included in the output. Here is an example output:

"results": {
    "missed_in_asic_db_routes": {
        "Vnet_v6": {
            "routes": [
                "fd01:fc00::1/128"
            ]
        }
    }
}

There is no output if there are no discrepancies between VNET routes in ASIC DB and APP DB.