Merge inspect and registry commands with network, paratime, account commands

[matevz]

Current inspect and registry platform-specific commands seem out of place compared to account, paratime and network commadns which are user-centric. As a rule-of-thumb, entity and validator operations go under account, consensus operations go under network and runtime operations go under paratime. I suggest we merge those accordingly:

• oasis registry runtime-register -> oasis paratime register
• oasis registry entity-register, oasis registry entity-deregister, oasis registry node-unfreeze could go under oasis account entity register, oasis account entity deregister, oasis account node-unfreeze
• oasis registry show -> oasis network show
• oasis inspect native-token -> oasis network info (in the future, this could also be added to oasis paratime for querying ParaTime-native tokens, but currently this is not supported yet anyway)
• oasis inspect node-status -> oasis network status
• oasis inspect runtime-stats -> oasis paratime stats
• oasis inspect governance-proposal -> oasis network governance-proposal
• oasis inspect block -> oasis paratime show