Refactor node creation in tests

[tzdybal]

There are multiple functions to create node instances. Lot of the code is duplicated. We should create single helper (function on struct) for creating nodes.

Configuration / possible inputs:

• context
• ABCI App
• is aggregator
• is full/light
• chain ID
• genesis / consensus params / ABCI params (VoteExtensionsEnableHeight in particular)
• persistence (DBPath in particular)
• DA implementation (to enable mocking)
  • or DA address & namespace for "default" config
• block manager config

For each possible input there should be a reasonable default value.

Possible outputs:

• Node (duh)
• App (may be needed if it was not provided)
• Keys (p2p key, signing key)

Originally mentioned in: #1641 (comment) and #1641 (comment).