env var CIRCUP_WEBWORKFLOW_PASSWORD

[FoamyGuy]

This adds support for an optional environment variable CIRCUP_WEBWORKFLOW_PASSWORD if set it's value will be used if the --password argument is omitted allowing the command to succeed if the variable contains the correct password.

e.g.

export CIRCUP_WEBWORKFLOW_PASSWORD="yourpassword"
circup --host 192.168.1.188 install adafruit_display_shapes

Help output for --password is updated to mention this new env variable.

This allows you to type less if you are manually entering commands as well as hide your password if you are streaming or using some other screenshare (if you export the variable off screen).

[tannewt]

Thank you!