add obstruction layers to user_project_wrapper to prevent router from using the area checked by xor

[mattvenn]

in a congested design, the router will use the area around the user_project_wrapper pins. this often results in an xor error with the open_mpw_precheck

either:

check less area in the precheck

or

add default obstruction layers protecting this area so the router doesn't use it.

[azwefabless]

This i a user project level issue outside of caravel and is being moved out of the caravel redesign issue. Belongs in user project wrapper.

[jeffdi]

@mattvenn is this still an issue?

[mattvenn]

I haven't seen it again, but don't know if it's solved or not

[jeffdi]

@kareefardi review current user_project_wrapper to see if this is still an issue.

[jeffdi]

If congested - there were cases where openlane was routing outside the PR boundary.

@marwaneltoukhy @kareefardi please review and close if no longer an issue.

[jeffdi]

suspect design to check

https://www.zerotoasiccourse.com/post/mpw2-submitted/