fix(deposits): Enforce deposit inclusion

[shotes]

This PR enforces that a deposit must be included in the proposed BeaconBlock.

WARNING: I do not believe this is backwards compatible IF a single validator on the chain has ever decided not to include a deposit. Do note that if every single validator so far is using our published binary, this should not be the case and the change should be completely backwards compatible. If this change is to be made, we should either:

1. Sync a node with this change to the chain to ensure no deposits have been excluded. If there has been a single instance of deposit exclusion, then the sync should fail. In that case, we have to...
2. Fork it

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.

Project coverage is 27.08%. Comparing base (419cd66) to head (f62217d).

Files with missing lines	Patch %	Lines
state-transition/core/validation_deposits.go	0.00%	5 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2407   +/-   ##
=======================================
  Coverage   27.08%   27.08%           
=======================================
  Files         351      351           
  Lines       15543    15543           
  Branches       20       20           
=======================================
  Hits         4210     4210           
  Misses      11130    11130           
  Partials      203      203           

Files with missing lines	Coverage Δ
state-transition/core/validation_deposits.go	0.00% <0.00%> (ø)

[abi87]

LGTM. Will approve as soon as we verify sync is fine