Label "Encryption Key" For Ed25519 is wrong

[ehanoc]

Describe the bug
When using Ed25519 keys, the label on hashicorp vault still calls it "Encryption Key". Ed25519 is a signature scheme and encryption can't be done directly with it. Therefore the option not even being available. But the label / nomenclature is wrong and might lead to confusion

To Reproduce
Steps to reproduce the behavior:

1. Use Transit Engine
2. Create Ed25519 Key
3. Choose Ed25519 key
4. Navigate to "Details" or "Versions"
5. Verify "Rotate" or "Edit" options refer to Ed25519 as "Encryption Key"

Expected behavior
Should refer to Ed25519 keys as "Signature Key"