fix: Iterate all ImageDebugDirectory entries

[Swatinem]

Turns out, a PE file can have more than one ImageDebugDirectory. Thus far, goblin only looks at the very first one, trying to interpret it as a CV record.

This code changes that logic to rather iterate over all the entries to find the one that is a CV record. We still only capture a single entry in the DebugData for backwards compatibility reasons. In the future we could as well capture all of them.

[Swatinem]

fun fact: I wrote a detailed blog post about how I made this discovery: https://swatinem.de/blog/format-ossification/

[m4b]

looks like a CI failure?