[testbed] announce routes with routes generation switch, aggregate routes and variable ipv6 address pattern

[w1nda]

Description of PR

Summary:
In this PR, we added new features to make announce routes script more powerful.

1. Variable ipv6 address pattern, previously, we are hardcoding ipv6 prefix with pattern 20%02X:%02X%02X:0:%02X::/64, now, it can be set in script or topology file.
2. Selectable exabgp setting up and routes generation. now we can add flag in topology file to enable ipv4 or ipv6, or disable ipv4 or ipv6.
3. Aggregated routes on peers. At the VM definition in topology file, we now support define aggregate route on the VM.

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• Test case(new/improvement)

Back port request

• 202012
• 202205
• 202305
• 202311
• 202405

Approach

What is the motivation for this PR?

To make route announcement more powerful.

How did you do it?

Add routes generation switch, aggregate routes and variable ipv6 address pattern

How did you verify/test it?

Verified on 7215 testbed with t0 and t1 topologies.

Any platform specific information?

Supported testbed topology if it's a new test case?

Documentation

[w1nda]

TODO:
Update routes announcement doc