Add new subcmds `denom set` and `denom set-native` and `denom remove`

[amela]

• oasis paratime denom set <network> <paratime> <denomination> <number_of_decimals> --symbol <symbol> (if someone sets denomination to _ it does not allow them to change denom, if symbol is not specified defaulting to <denomination>)
• oasis paratime denom set-native <network> <paratime> <denomination> <number_of_decimals>
• oasis paratime denom remove <network> <paratime> <denomination>