Move checked-out code into its own directory, point workspace location

[rfay]

Currently we have code being checked out as a subdirectory of ddev-gitpod-launcher and that's just ugly and confusing.

It turns out that .gitpod.yml has an option called workspaceLocation (see https://www.gitpod.io/docs/checkout-location, thanks @shaal )

• Check out the target project (like d9simple) into /workspace/code (or something)
• Set workspaceLocation to /workspace/code
• Fix the launch.json path mappings to use /workspace/code

[rfay]

This would definitely be an improvement.

[tyler36]

#39 fixes:

• ✅ Check out the target project (like d9simple) into /workspace/code (or something)
• ✅ Set workspaceLocation to /workspace/code