workspace: fix pointer scanning, add duplicate prefix error

[BrettMayson]

Checks /include/, /optionals/, /addons/ for prefix files instead of /

Adds a new error if there are any duplicate prefix files

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 68.75000% with 10 lines in your changes missing coverage. Please review.

Project coverage is 69.2%. Comparing base (8216250) to head (6078b78). Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
libs/workspace/src/lib.rs	68.7%	10 Missing :warning:

Additional details and impacted files

| [Files with missing lines](https://app.codecov.io/gh/BrettMayson/HEMTT/pull/814?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Brett) | Coverage Δ | | |---|---|---| | [libs/common/src/prefix.rs](https://app.codecov.io/gh/BrettMayson/HEMTT/pull/814?src=pr&el=tree&filepath=libs%2Fcommon%2Fsrc%2Fprefix.rs&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Brett#diff-bGlicy9jb21tb24vc3JjL3ByZWZpeC5ycw==) | `96.9% <ø> (ø)` | | | [libs/workspace/src/lib.rs](https://app.codecov.io/gh/BrettMayson/HEMTT/pull/814?src=pr&el=tree&filepath=libs%2Fworkspace%2Fsrc%2Flib.rs&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Brett#diff-bGlicy93b3Jrc3BhY2Uvc3JjL2xpYi5ycw==) | `89.1% <68.7%> (-5.3%)` | :arrow_down: |