## Description 

Improves how the `keytool convert` command is displayed by explicitly
showing the output's encoding: base64 or hex

## Test Plan 


![image](https://github.com/MystenLabs/sui/assets/135084671/eb8a3acd-6a3a-4d78-99b6-fa2e2916db86)

---
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### Type of Change (Check all that apply)

- [ ] protocol change
- [ ] user-visible impact
- [ ] breaking change for a client SDKs
- [ ] breaking change for FNs (FN binary must upgrade)
- [ ] breaking change for validators or node operators (must upgrade
binaries)
- [ ] breaking change for on-chain data layout
- [ ] necessitate either a data wipe or data migration

### Release notes