Add filtering of postCreateCommand stdout stderr logs

[janekbaraniewski]

Fixes issue where everything sent to stderr by postCreateCommand was logged as error by devpod

13:15:27 info Creating devcontainer...
13:15:27 info Inspecting image mcr.microsoft.com/vscode/devcontainers/python
13:15:27 info a8e8a369f917aa05b34e84a115077384c4c63d9c09cd12904d0c7672003966f9
13:15:28 info Setup container...
13:15:29 info Chown workspace...
13:15:29 info Run command : pipx install uv...
13:15:29 error creating virtual environment...
13:15:29 error installing uv...
13:15:30 error done! ✨ 🌟 ✨
13:15:30 info installed package uv 0.2.18, installed using Python 3.12.3
13:15:30 info These apps are now globally available
13:15:30 info - uv
13:15:30 done Successfully ran command : pipx install uv
13:15:30 info Install extensions 'dbaeumer.vscode-eslint,ms-python.python,ms-python.vscode-pylance,ms-python.autopep8' in the background
13:15:30 info Run 'ssh minimal-example.devpod' to ssh into the devcontainer
13:15:30 info Starting VSCode...

Now those will appear as warning level log unless they're actual errors:

15:17:01 info Creating devcontainer...
15:17:01 info Deleting devcontainer...
15:17:02 info Inspecting image mcr.microsoft.com/vscode/devcontainers/python
15:17:02 info 9c2e1cf2064e71dc36e7efe2ba99c3983766e725dd32ddf4313bfa0dd45d9905
15:17:02 info Setup container...
15:17:02 info Chown workspace...
15:17:02 info Run command : pipx install uv...
15:17:02 warn creating virtual environment...
15:17:03 warn installing uv...
15:17:04 warn done! ✨ 🌟 ✨
15:17:04 info installed package uv 0.2.22, installed using Python 3.12.3
15:17:04 info These apps are now globally available
15:17:04 info - uv
15:17:04 info - uvx
15:17:04 done Successfully ran command : pipx install uv
15:17:04 info Install extensions 'dbaeumer.vscode-eslint,ms-python.python,ms-python.vscode-pylance,ms-python.autopep8' in the background
15:17:04 info Run 'ssh minimal-example.devpod' to ssh into the devcontainer
15:17:04 info Starting VSCode...