node: updates for node.Config

[Wondertan]

Context

Work on #30 turns out quite big and to follow the practice of keeping PR relatively small, I've extracted some work related to configs into separate PR

Changes

• Simplify and prettify FullNode tests
• Extract node.Config into a new subpackage to avoid circular dependencies
• De/serialization functions for Config
• Use Config value everywhere instead of pointers
  • Pointers create issues with serialization which can be fixed using mapstructure, but that is some additional complexity that does no make sense for me.
  • If you have arguments against using values for Config - pls bring them up, because I don't get the.
• New FX utility

[renaynay]

I'm okay with these changes. I don't really like passing the core config directly to the new full node but it's fine.

[liamsi]

👍🏼

[Wondertan]

I've moved back the Config to node, as there is another solution to dep cycle and I still prefer to keep Config in the node package, so it is clear that is related to the node by just looking into node.Config.

[Wondertan]

Also, I've changed the toml parser to BurntSushi/toml from pelletier/go-toml/v2 as the latter does not support Config parsing of Tendermint config needed in #81, as having two parsers is not good, even if the latter is much better in terms of performance.

[liamsi]

👏🏼 nothing to complain about.

[Wondertan]

Shipit-tipihS