go/oasis-node/cmd/node: Log the version on startup

[Yawning]

Might as well, though it won't show up at the default log level.

Fixes #2663.

[codecov]

Codecov Report

Merging #2998 into master will decrease coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2998      +/-   ##
==========================================
- Coverage   68.60%   68.54%   -0.06%     
==========================================
  Files         360      360              
  Lines       35379    35382       +3     
==========================================
- Hits        24270    24251      -19     
- Misses       7982     7999      +17     
- Partials     3127     3132       +5     

Impacted Files	Coverage Δ
go/oasis-node/cmd/node/node.go	58.70% <100.00%> (+2.86%)	⬆️
go/consensus/tendermint/abci/state/state.go	61.53% <0.00%> (-7.70%)	⬇️
go/common/grpc/policy/policy.go	64.38% <0.00%> (-6.85%)	⬇️
.../consensus/tendermint/apps/epochtime_mock/state.go	78.72% <0.00%> (-4.26%)	⬇️
go/storage/metrics.go	78.26% <0.00%> (-3.27%)	⬇️
go/worker/compute/executor/committee/node.go	62.57% <0.00%> (-2.69%)	⬇️
go/storage/api/root_cache.go	70.11% <0.00%> (-2.30%)	⬇️
go/consensus/tendermint/abci/state.go	67.27% <0.00%> (-2.19%)	⬇️
go/worker/compute/txnscheduler/committee/node.go	61.26% <0.00%> (-2.11%)	⬇️
go/storage/database/database.go	70.58% <0.00%> (-1.69%)	⬇️
... and 16 more

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