Implement Vault for secret management and key rotation

[i5okie]

Inventory of Credentials

Notes added after initial assessment

Secret Name	Key	Type	Instances	Notes
aries-endorser-agent	admin-api-key	API Key	ACA-Py Agent	Used by controllers, sometimes external, to authenticate with the Admin API. In the case of an endorser service the controller is the internal endorser API.
aries-endorser-agent	webhook-url	API Key	ACA-Py Agent	Only the API key portion of the webhook URL is rotatable. This is used by ACA-Py to authenticate with it's associated, sometimes external, controller's webhook endpoint. In the case of an endorser service the controller is the internal endorser API.
aries-endorser-agent-wallet-credentials	DID	DID	ACA-Py Agent	NOT Rotatable
aries-endorser-agent-wallet-credentials	key	Wallet Key	ACA-Py Agent	The wallet encryption key. The process to rotate wallet keys can be complicated.
aries-endorser-agent-wallet-credentials	seed	Wallet Seed	ACA-Py Agent	The DID's seed. The seed itself can not be rotated (confirm this), however the keys associated to a DID can be rotated. The process to rotate a DIDs keys can be complicated.
aries-endorser-api	admin-api-key	API Key	Endorser API	Used by controllers, possibly external, to authenticate with the endorser API.
aries-endorser-api	webhook-api-key	API Key	Endorser API	Used by the associated ACA-Py instance to authenticate with the endorsers webhook endpoint.
aries-endorser-db	admin-password	password	Endorser DB	The admin password for the database instance.
aries-endorser-db	admin-user	username	Endorser DB	The admin username for the database instance.
aries-endorser-db	database-name	database name	Endorser DB	NOT Rotatable
aries-endorser-db	database-password	password	Endorser DB	The password associated to the database-user account.
aries-endorser-db	database-user	username	Endorser DB	The username of the account used by the application for database access.
aries-endorser-wallet	admin-password	password	ACA-Py Wallet Database	The admin password for the wallet's database instance.
aries-endorser-wallet	database-name	database name	ACA-Py Wallet Database	NOT Rotatable
aries-endorser-wallet	database-password	password	ACA-Py Wallet Database	The password associated to the database-user account.
aries-endorser-wallet	database-user	username	ACA-Py Wallet Database	The username of the account used by the application for wallet database access.