Description

apisix/secret/vault.lua was introduced in #8412.

Functions currently in apisix/secret/vault.lua are copied from apisix/core/vault.lua.

The functions in apisix/core/vault.lua are only used in the jwt-auth plugin to save the jwt key, so it is not appropriate to put vault-related functions in the core module. We need to unify them.

The kms component has more comprehensive key management functions and is more versatile, so we should make the following adjustments:

1. Use the vault function provided by the kms component to replace the vault-related functions in the jwt-auth plugin. This will introduce a break change due to changes in configuration.
2. Delete the apisix/core/vault.lua file.