Go: Fix buggy FindAllFilesWithName implementation

[mbg]

Summary

It seems that our implementation of FindAllFilesWithName contained bugged logic where dirsToSkip was typically given a list of directory names (such as vendor) and then compared these to the relative path of directories discovered by filepath.WalkDir (such as ./vendor). This resulted in go.mod and go.work files in vendor directories not getting skipped correctly, which was reported in #17893.

Approach

@smowton implemented a handy isGolangVendorDirectory predicate as part of #17227, which already implements the correct check. To not duplicate this logic, I decided to move isGolangVendorDirectory from that package to the shared util one. I then modified FindAllFilesWithName to accept such predicate functions as arguments instead of an array of strings. I changed calls to FindAllFilesWithName to use a (pre-defined) array containing the isGolangVendorDirectory predicate instead of the "vendor" string.

I then added a problematic vendor directory to the mixed-layout integration test, containing a go.work file.

Alternatives

Instead of modifying FindAllFilesWithName to accept a list of predicates, we could just check that each path discovered by filepath.WalkDir ends in one of the excluded directory names.

Open questions

• As part of Go: Add environment variable to include vendor directories in extraction #16925 and Go / configure-baseline: account for multiple vendor directories and the CODEQL_EXTRACTOR_GO_EXTRACT_VENDOR_DIRS setting #17227 we only modified the extractor logic for extracting vendor directories that are contained within some other workspace. We didn't modify the autobuilder's project discovery logic to also permit finding workspaces in vendor directories. While making the changes for this fix, it wasn't clear to me what the autobuilder's workspace discovery project should do if CODEQL_EXTRACTOR_GO_EXTRACT_VENDOR_DIRS is set to true.

[owen-mc]

There are failing integration tests that need to be fixed.

It seems broadly sensible. It seems a bit odd to have the functionality to specify arbitrary directories to skip when we only ever use it for vendor directories. It might be simpler to either always skip vendor directories or have a boolean for skipping them. I'm unsure of the right thing to do when CODEQL_EXTRACTOR_GO_EXTRACT_VENDOR_DIRS is true - I guess we should look for go.work and go.mod files in vendor directories in that case, but I defer to @smowton when he is back.