Fallback to system resolve if error file path not relative

[worksofliam]

Changes

Fixes #1944, where if you had a member include from your local compile, it was not resolving in the Problems view correctly.

How to test this PR

1. Run the test cases

Example file:

**free
// put this in YOURLIB/ASRCPF/AMBR.RPGLE
dcl-c MYNUMBER 27;

**free

# put this in your local workspace

/copy yourlib/asrcpf,ambr

dcl-s mytext char(1);

mytext = '1';

return;

After compiling the local workspace file, you should see the info message point to the member correctly.

Checklist

• have tested my change
• have created one or more test cases
• updated relevant documentation
• Remove any/all console.logs I added
• have added myself to the contributors' list in CONTRIBUTING.md

[william-xiang]

@sebjulliand Could you review this PR when you have time?
It works for me in both local vscode and merlin.

[eric-simpson]

@sebjulliand Seb, can you review this?

[worksofliam]

@william-xiang If you have tested and are happy then I will accept your review.

[sebjulliand]

@worksofliam @eric-simpson @william-xiang sorry, it was quite busy these days.
Anyway, I tested it, tried a few different kind of include paths and it works just fine.
I pushed a small cleanup commit.
@worksofliam feel free to merge whenever you want.