Publish org.processing.core.dxf to Maven Central (Publish libraries to maven central)

[Stefterv]

Context:
https://discord.com/channels/1076634729618624534/1229526727320146042/1468237872074068141

• DXF

Test is currently running on my repo results should show up here: https://central.sonatype.com/search?q=g%3Anl.steftervelde.java.libraries

[Stefterv]

@avinxshKD would you be interested in applying the same to some of the other Java Libraries?

[avinxshKD]

@Stefterv Sure, I can take a look at those.

Breakdown looks like this:

• PDF: Good to go. It already has the Gradle setup, just needs the publishing block.

• Net / SVG: Need to be fully ported from Ant to Gradle first, but otherwise straightforward.

• Serial / IO: These are harder because of the native libs/JARs. We'll need to figure out how to package those correctly for Maven so we don't break cross-platform support.

One catch on this PR: build.gradle.kts lists implementation("com.lowagie:itext:2.1.7"). pretty sure that's a copy-paste error from the PDF library? DXF shouldn't depend on iText.

[Stefterv]

Great! Just make individual PR's for each package starting with the easiest.

And thanks for catching the dependency!