support multiple data flag usage

[reubenmiller]

Change data flag from string to stringArray which allows the user to use data flag multiple times in the same command. This makes the command a bit more readable when setting multiple fields.

Example

Create a new device

Create a new device my combining the template and data usage. Use multiple data flags to make the command a bit more readable as it can be split across multiple lines.

c8y devices create \
    --name "Test device" \
    --template "{c8y_SupportedOperations:['c8y_Command', 'c8y_Restart']}" \
    --data "subtypes=[linuxA,linuxB]" \
    --data "c8y_Hardware.model=linux" \
    --data "c8y_Hardware.serial=abcdef" \
    --dry

Body

{
  "c8y_Hardware": {
    "model": "linux",
    "serial": "abcdef"
  },
  "c8y_IsDevice": {},
  "c8y_SupportedOperations": ["c8y_Command", "c8y_Restart"],
  "name": "Test device",
  "subtypes": ["linuxA", "linuxB"]
}