e2etest support for rolldpos

[envestcc]

What would you like to be added

as title

Why is this needed

Currently, e2etest only supports standalone mode and cannot cover testing in aspects such as consensus and p2p

How important you think this is for IoTeX

• nice to have

Additional information

Let us know any background or context that would help us better understand the request (for example the particular use-case that prompted this request)