feat: add improved logging around devcontainer.json lifecycle commands

# Problem

If you are trying to troubleshoot post create commands etc. it is difficult right now to know if 
a) your postCreateCommand is not getting run, or
b) it is getting run but not emitting any output

# Proposed Solution

Add debug-level logging when building a devcontainer around the following:
- Lifecycle script is not present
- Lifecycle script is present but empty