Define types for CLI options "stage" and "password"

[vijay-immanent]

CLI options definitions were upgraded with "type" property (which could be one of "string", "boolean", "multiple"). 
Below listed plugins do not predefine type for introduced options:
 - ServerlessSecretsPlugin for "stage", "password"

"serverless-secrets-plugin": "^0.1.0"

$ serverless --verison

Running "serverless" from node_modules Framework Core: 3.15.0 (local) 3.7.9 (global) Plugin: 6.2.2 SDK: 4.3.2