pw_cli: Add PW_CONSOLE_CONFIG_FILE env var

Add PW_CONSOLE_CONFIG_FILE as a recognized environment variable. See:
https://pigweed.dev/pw_console/py/pw_console/docs/user_guide.html#configuration

Change-Id: I634eebabb195718f9531a7145e54f3767a0fe943
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/78140
Pigweed-Auto-Submit: Anthony DiGirolamo <tonymd@google.com>
Reviewed-by: Carlos Chinchilla <cachinchilla@google.com>
Commit-Queue: Anthony DiGirolamo <tonymd@google.com>
diff --git a/pw_cli/py/pw_cli/env.py b/pw_cli/py/pw_cli/env.py
index b26b42d..c1e4775 100644
--- a/pw_cli/py/pw_cli/env.py
+++ b/pw_cli/py/pw_cli/env.py
@@ -58,6 +58,7 @@
     parser.add_var('PW_PRESUBMIT_DISABLE_SUBPROCESS_CAPTURE',
                    type=envparse.strict_bool)
 
+    parser.add_var('PW_CONSOLE_CONFIG_FILE')
     parser.add_var('PW_ENVIRONMENT_NO_ERROR_ON_UNRECOGNIZED')
 
     return parser