Add IntelliJ troubleshooting tips to BUILD.md

[marioguzzzman]

This PR adds a new section to BUILD.md with troubleshooting tips for using IntelliJ IDEA, including:

• Selecting the correct JDK (temurin-17)
• Steps to download the right JDK via IntelliJ
• Explaining the “Duplicate content roots detected” warning

Screenshots included for clarity.

Thanks again @Stefterv and @SableRaf for the green light!

Closes#1095

[Stefterv]

Great! Can you add the images to the repo, we don't have a guarantee that the GitHub attachments will live forever.

[marioguzzzman]

Yes, I can. Should I just add a build_troubleshooting folder in at the same level as the BUILD.md? is there a preferred way to add this images?

[Stefterv]

I would suggest adding them to a .github/media folder for now, I'd like to keep the top level folders clean. @SableRaf can you input on this as well?

[SableRaf]

I would suggest adding them to a .github/media folder for now

I was about to say the same :)

[marioguzzzman]

Great media-synching thoughts there ;)

Screenshots are now added in .github/media and linked in BUILD.md as suggested

Let me know if you'd like any adjustments!