Added toolchain to autodetect jdk

[joachimnielandt]

I had some trouble when building locally, as javac wasn't detected properly. Only after setting my OS-wide Java to v11 it built successfully. I remembered Geonetwork used toolchains though, which I added here as well. Does that make sense in this context?

Took the opportunity to tidy up some whitespace issues as well...

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

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