Add stress and performance test for BGP suppress fib pending feature

[echuawu]

Why I did it

Requirements from MSFT for BGP suppress fib pending feature:

1. Add a stress test that test at least 1K bgp route announce and withdraw 5 ~ 10 times for consistence test.
2. Add a performance test that measures at least 1K bgp route process performance by tcpdump

How I did it:

1. For the specific implementation, it's under discussion with MSFT

How to verify it:

1. Using tcpdump to calculate the bgp routes handle performance

[yxieca]

Seems that work is done.

[stephenxs]

I believe it should be Stepan @stepanblyschak :)

[stepanblyschak]

@roy-sror Please assign relevant owner

[roy-sror]

@stepanblyschak - Done, @echuawu will implement in Nov.

[echuawu]

@StormLiangMS , for the usage of tcpdump in this test, do you have some use case of existing performance test?