go/consensus/cometbft/api: Simplify consensus service client

[peternose]

This will remove DeliverCommand from consensus ServiceClient, making the API more clean and limited only to two methods DeliverBlock and DeliverEvents. As a result, anyone with access to blocks and events can now run the client.

[netlify]

✅ Deploy Preview for oasisprotocol-oasis-core canceled.

Name	Link
🔨 Latest commit	e1842bc
🔍 Latest deploy log	https://app.netlify.com/sites/oasisprotocol-oasis-core/deploys/67f59986012e580008f6213f

[martintomazic]

Hats of for this PR(!), as it simplifies our code significantly.

I left one minor question... :)

[codecov]

Codecov Report

Attention: Patch coverage is 75.69061% with 44 lines in your changes missing coverage. Please review.

Project coverage is 65.12%. Comparing base (a97e93e) to head (e1842bc).
Report is 10 commits behind head on master.

Files with missing lines	Patch %	Lines
go/consensus/cometbft/roothash/roothash.go	68.18%	23 Missing and 5 partials ⚠️
go/consensus/cometbft/full/services.go	88.00%	4 Missing and 5 partials ⚠️
go/consensus/cometbft/full/archive.go	20.00%	3 Missing and 1 partial ⚠️
go/consensus/cometbft/full/full.go	57.14%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6137      +/-   ##
==========================================
- Coverage   65.26%   65.12%   -0.15%     
==========================================
  Files         637      637              
  Lines       64575    64524      -51     
==========================================
- Hits        42147    42022     -125     
- Misses      17539    17579      +40     
- Partials     4889     4923      +34     

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