pw_env_setup: Fix banner printing on Windows

- Fix colors load import error when runnning activate.bat on windows.
- Load PW_BRANDING_BANNER if it exist in windows_env_start.py
- Always load the branding banner files as utf-8

Bug: b/289008307
Change-Id: Ifada33d65da7cb152172197baedb15f97a09eb5b
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/169172
Commit-Queue: Auto-Submit <[email protected]>
Reviewed-by: Armando Montanez <[email protected]>
Pigweed-Auto-Submit: Anthony DiGirolamo <[email protected]>

pw_cli/py/pw_cli/branding.py

@@ -42,7 +42,7 @@ def banner() -> str:
     # Take the banner from the file PW_BRANDING_BANNER; or use the default.
     banner_filename = parsed_env.PW_BRANDING_BANNER
     _memoized_banner = (
-        Path(banner_filename).read_text()
+        Path(banner_filename).read_text(encoding='utf-8', errors='replace')
         if banner_filename
         else _PIGWEED_BANNER
     )

pw_env_setup/py/pw_env_setup/windows_env_start.py

@@ -26,7 +26,12 @@
 import os
 import sys
 
-from .colors import Color, enable_colors  # type: ignore
+try:
+    from pw_env_setup.colors import Color, enable_colors
+except ImportError:
+    # Load from this directory if pw_env_setup is not available.
+    from colors import Color, enable_colors  # type: ignore
+
 
 _PIGWEED_BANNER = u'''
  ▒█████▄   █▓  ▄███▒  ▒█    ▒█ ░▓████▒ ░▓████▒ ▒▓████▄
@@ -42,7 +47,21 @@ def print_banner(bootstrap, no_shell_file):
     enable_colors()
 
     print(Color.green('\n  WELCOME TO...'))
-    print(Color.magenta(_PIGWEED_BANNER))
+
+    banner_file = os.environ.get('PW_BRANDING_BANNER', None)
+    banner_str = None
+    if banner_file:
+        try:
+            banner_str = open(
+                banner_file, 'r', encoding='utf-8', errors='replace'
+            ).read()
+        except FileNotFoundError:
+            pass
+    if banner_str:
+        print()
+        print(banner_str, end='')
+    else:
+        print(Color.magenta(_PIGWEED_BANNER), end='')
 
     if bootstrap:
         print(