Namespace phase0 types

[wemeetagain]

This namespaces ssz types under config.types.phase0 or import {phase0} from "@chainsafe/lodestar-types";
This allows us to always refer unambiguously to a specific version of a type.
It also allows us to add types for future HFs without breaking the 'backward compatibility' of the existing types.

This PR creates IPhase0Params and IPhase0SSZTypes and integrates them in the params and types libraries in a standard way.

Future HF params are expected to define new params and never update the value of a pre-existing param. IBeaconParams will be the union of all HF params.
(eg: type IBeaconParams = IPhase0Params & IHFParams ....;)

Future HF ssz types are expected to define new types and possibly update existing types (but only by adding additional fields to those types).
IBeaconSSZTypes will have a separate namespace for each HF that allows for unambiguously selecting a type at a specific version.
(eg: type IBeaconSSZTypes = { phase0: IPhase0SSZTypes; hf: IHFSSZTypes };)
These same namespaces are exported from the root of the @chainsafe/lodestar-types to access the typescript types.
(eg: import {phase0, hf} from "@chainsafe/lodestar-types";)

For improved ergonomics, a few tweaks have been made.
Primitive types are also available directly on IBeaconSSZTypes and are also exported from the roof of @chainsafe/lodestar-types. This list of un-namespaced types may only ever grow to include types that we know will never change, to protect backwards compatibility.

Additionally, phase0 typescript types have been re-exported under phase0 exports in @chainsafe/lodestar-beacon-state-transition. This allows importing a single phase0 object from @chainsafe/lodestar-beacon-state-transition to both access phase0 state transition functions AND phase0 typescript types.

[codeclimate]

Code Climate has analyzed commit 301d609 and detected 36 issues on this pull request.

Here's the issue category breakdown:

Category	Count
Duplication	36

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[mpetrunic]

SSo many changed files, even octotree extension has frozen haha