Adjust `GenesisBuilder` naming

[michalkucharczyk]

GenesisBuilder trait needs some naming adjustments.

          LGTM other than a grumble about naming which I hope to see fixed before this is stabilized.

Originally posted by @kianenigma in paritytech/substrate#14310 (review)

Refer also to: paritytech/substrate#14131 (review)

part of: #25

[kianenigma]

To re-iterate, I have two points:

1. We are using the word "config", where it is meant to just represent "state". For example fn build_config(config: Vec<u8>, param: Vec<u8>) -> sp_genesis_builder::Result which is now part of all runtimes is doing nothing other than building the initial "state". Why are we calling this "config"? there is no "configuration" involved.
2. And, the former point is important, because is FRAME Config means something specific, and I worried that people would mix the two.

[JoshOrndorff]

This is relevant to what we are doing in Off-Narrative-Labs/Tuxedo#127 (cc @muraca) and my question at https://substrate.stackexchange.com/questions/10105/extrinsics-in-genesis-block

IDK if it is in scope for this issue, but we are wanting to allow chain launchers to specify genesis transactions (yes transactions, not just state) in their chain specs. But have so far relied on a storage hack.

[michalkucharczyk]

IDK if it is in scope for this issue, but we are wanting to allow chain launchers to specify genesis transactions (yes transactions, not just state) in their chain specs. But have so far relied on a storage hack.

This issue is only about re-naming the components that are already in place (e.g : GenesisBuilder API), which were implemented to add support for GenesisConfig in wasm runtimes. (refer to: #25).

Adding support for genesis extrinsic is definitely out of scope of this ticket.

[bkchr]

IDK if it is in scope for this issue, but we are wanting to allow chain launchers to specify genesis transactions (yes transactions, not just state) in their chain specs. But have so far relied on a storage hack.

This is already supported, as I have answered you on SE.

[michalkucharczyk]

New naming proposed in #2714 (cc: @kianenigma)