Implement type spec tests

[Zacholme7]

Implementation for the types spec tests. Gave myself a week for these and think it may be time to just clean this all up and call them good. This PR contains the work in #374 and #377 as everything got a bit our of line so I decided to just merge everything together. This is a giga PR so I can also try to break it up.

I would say the main use for these is to test our SSZ encoding/decoding, which we can now confirm is spec compliant. There really may even be an argument that we should only include the ssz encoding/decoding and consider what we can scrap.

I have also deemed a few to be skippable

• The committee member tests as our types differ substantially here and it would be a couple hundred lines of just parsing for basic quorum validation. I can just write a unit tests if this is really needed
• The beacon deposit data test. This generates ETH deposit data, but this is never actually even used in the client.
• The duty tests. These are for their internal runner mapping which is an implementation detail, not spec level.
• The share encoding test. We use a different structure for share data so it does not make sense to test this encoding.

There are also some tests with data issues that I have raised

• The ssv message tests use message ids that should not be considered valid for the testing scenario. I have addresses this here
• the ssz test uses data from a beacon block with mocked signatures which when we try to parse into BeaconBlock, fails with BLST_BAD_ENCODING. Raised the issue here

[Zacholme7]

Currently blocked on #416 getting merged in