Overwrite protection when generating keys and storing in a vault

[chris-j-h]

The keys in a vault can be overwritten if new keys are generated with the same name

Tessera should check if keys already exist with the provided name and if so, provide a prompt to the user confirming if they want to overwrite these values.

[chris-j-h]

Additionally, Hashicorp key generation currently sets the key names as publicKey and privateKey. Providing the ability to set custom names would also help prevent keys from being overwritten.

[chris-j-h]

This issue has been closed as an alternative resolution was used. With #565 and #574, Tessera can retrieve the previous versions of a secret stored in an Azure or Hashicorp vault, thereby preventing a complete overwrite of the values stored in the vault.