Mark specific Configuration Items as Secret

Feature description
Allow developers to flag a config item as "Secret" so that cortexutils can hide it in error messages.
Add the info in "How to Write and Submit an Analyzer" documentation.

Additional context
In some cases, an error in a Cortex-Analyzer code can reveal the API keys, like shown in the following image.

Complementary information
This is my config file

{
  "name": "FalconSearchIOC",
  "author": "Norgalades",
  "license": "AGPL-V3",
  "url": "https://github.com/",
  "version": "1.0",
  "description": "Check if an IOC (IP, domain or hash) has been seen in your CrowdStike environment.",
  "dataTypeList": ["ip", "hash", "domain"],
  "baseConfig": "FalconSearchIOC",
  "command": "FalconSearchIOC/falcon_search_IOC.py",
  "configurationItems": [
    {
      "name": "cs_api_off",
      "description": "Office api",
      "type": "string",
      "multi": false,
      "required": true
    },
    {
      "name": "cs_api_aff",
      "description": "Aff api",
      "type": "string",
      "multi": false,
      "required": true
    }
  ]
}

Start with the configurationItems section in the example configuration and read the “How to Write and Submit an Analyzer” documentation. Determine how a specific item can be marked Secret so cortexutils hides its value from error messages, then update that documentation and verify that API keys are no longer exposed.