Output of the pip or other packages should be improved to give more informative installation errors.

Reproduce the failure with sam build, then start at aws_lambda_builders/workflows/python_pip/packager.py, especially download_all_dependencies and its pip error handling. Trace how package-installation output is decoded and determine what informative error output should be preserved; done means the reported installation failure is understandable instead of ending in a UnicodeDecodeError.

Description:

Steps to reproduce the issue:
sam build

Observed result:

Telemetry endpoint configured to be https://aws-serverless-tools-telemetry.us-west-2.amazonaws.com/metrics
'build' command is called
No Parameters detected in the template
2 resources found in the template
Found Serverless function with name='HelloWorldFunction' and CodeUri='hello_world/'
No Parameters detected in the template
Building function 'HelloWorldFunction'
Loading workflow module 'aws_lambda_builders.workflows'
Registering workflow 'PythonPipBuilder' with capability 'Capability(language='python', dependency_manager='pip', application_framework=None)'
Registering workflow 'NodejsNpmBuilder' with capability 'Capability(language='nodejs', dependency_manager='npm', application_framework=None)'
Registering workflow 'RubyBundlerBuilder' with capability 'Capability(language='ruby', dependency_manager='bundler', application_framework=None)'
Registering workflow 'GoDepBuilder' with capability 'Capability(language='go', dependency_manager='dep', application_framework=None)'
Registering workflow 'GoModulesBuilder' with capability 'Capability(language='go', dependency_manager='modules', application_framework=None)'
Registering workflow 'JavaGradleWorkflow' with capability 'Capability(language='java', dependency_manager='gradle', application_framework=None)'
Registering workflow 'JavaMavenWorkflow' with capability 'Capability(language='java', dependency_manager='maven', application_framework=None)'
Registering workflow 'DotnetCliPackageBuilder' with capability 'Capability(language='dotnet', dependency_manager='cli-package', application_framework=None)'
Registering workflow 'CustomMakeBuilder' with capability 'Capability(language='provided', dependency_manager=None, application_framework=None)'
Found workflow 'PythonPipBuilder' to support capabilities 'Capability(language='python', dependency_manager='pip', application_framework=None)'
Running workflow 'PythonPipBuilder'
Running PythonPipBuilder:ResolveDependencies
calling pip download -r C:\zang\sam\sam-app\hello_world\requirements.txt --dest C:\Users\120000843\AppData\Local\Temp\tmpolmpbuso
PythonPipBuilder:ResolveDependencies raised unhandled exception
Traceback (most recent call last):
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\lib\site-packages\aws_lambda_builders\workflow.py", line 269, in run
action.execute()
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\lib\site-packages\aws_lambda_builders\workflows\python_pip\actions.py", line 42, in execute
requirements_path=self.manifest_path,
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\lib\site-packages\aws_lambda_builders\workflows\python_pip\packager.py", line 137, in build_dependencies
self._dependency_builder.build_site_packages(requirements_path, artifacts_dir_path, scratch_dir_path)
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\lib\site-packages\aws_lambda_builders\workflows\python_pip\packager.py", line 204, in build_site_packages
wheels, packages_without_wheels = self._download_dependencies(scratch_directory, requirements_filepath)
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\lib\site-packages\aws_lambda_builders\workflows\python_pip\packager.py", line 228, in _download_dependencies
deps = self._download_all_dependencies(requirements_filename, directory)
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\lib\site-packages\aws_lambda_builders\workflows\python_pip\packager.py", line 310, in _download_all_dependencies
self._pip.download_all_dependencies(requirements_filename, directory)
File "C:\Program Files\Amazon\AWSSAMCLI\runtime\lib\site-packages\aws_lambda_builders\workflows\python_pip\packager.py", line 595, in download_all_dependencies
error = err.decode()
UnicodeDecodeError: 'utf-8' codec can't decode byte 0x91 in position 565: invalid start byte

Expected result:
Output of the pip or other packages should be improved to give more informative installation errors.
Additional environment details (Ex: Windows, Mac, Amazon Linux etc)