bucket notifications - add action to encrypt connection file

[alphaprinz]

Explain the changes

Before this change the connection file was completely plain text, including the http basic authentication header.
This change adds API to manipulate connection files, adding the logic to encrypt this field when a connection file is created.

The new CONNECTION type is introduced, along with standard CRUD actions.
The 'STATUS' action also includes a 'decrypt' flag to decrypt connection file into plain text.

Issues: Fixed #xxx / Gap #xxx

1. password is getting exposed in connections_kv.json file  #8643

Testing Instructions:

1. Using manage_nsfs cli, create a connection with the "auth" option under request_options_object.
2. The auth field is encrypted.
3. Notifications work as intended using the connection. IE, auth header is sent in plain text.

• Doc added/updated
• Tests added