Creates a random password string. The length of the generated string
is determined by the _password_length parameter. It is taken from the
context first. If it is not found in the context, it is read from the
activity definition instead. If neither is defined, a default length of 16
Optionally, the action parameter password_policy may be set to specify
the password policy to apply to the generated password.
The currently supported policies are:
<B>Note:B> The tuncate done by the the password_length parameter. This value
must fit to the selected password policy.
The password will consist of one or more lowercase letters and one or more
digits, with a minimum of 5 characters. No other characters (e.g. symbols)
The generated random string is written to the context parameter