Add option to write the `value` from prompt if `value` is not provided

[nitrocode]

It would be nice to get a prompt if the value is omitted during a write operation

This would still work

$ chamber write service key value
<secret stored>
$

If value is omitted, then it could prompt

$ chamber write service key
A value was not provided, please provide it in the secure prompt below and press enter.
<user types in secret and it does not show up visually>
<user presses enter>
<secret stored>
$

[bhavanki]

It doesn't really address the request here, but passing a value of - to chamber write has chamber read the value from standard input. There is no prompt, and the value being typed is echoed back. If the secret value is piped in from a file, though, it wouldn't appear. Something like:

chamber write service key - < mysecret.txt

[emmanuelnk]

Facing the same issues above, I just decided to write custom bash functions to do prompts properly:

# write to parameter store
chamber_write_to_ssm() {
  export CHAMBER_KMS_KEY_ALIAS=aws/ssm
  local service_name=$1
  local secret_key=$2

  shift 2
  echo -n "Enter secret value for $secret_key (input will be hidden): "
  read -s secret_value
  echo

  chamber write "$service_name" "$secret_key" "$@" -- "$secret_value"
}

# write to secrets manager
chamber_write_to_smr() {
  export CHAMBER_KMS_KEY_ALIAS=aws/secretsmanager
  local service_name=$1
  local secret_key=$2

  shift 2
  echo -n "Enter secret value for $secret_key (input will be hidden): "
  read -s secret_value
  echo

  chamber write "$service_name" "$secret_key" -b secretsmanager "$@" -- "$secret_value"
}