Split photon-server and photon-core (#211)

Uses multiple Gradle projects to support the split.

photon-core/versioningHelper.gradle

@@ -0,0 +1,46 @@
+import java.time.LocalDateTime
+import java.time.format.DateTimeFormatter
+import java.nio.file.Path
+
+gradle.allprojects {
+    ext.getCurrentVersion = { ->
+        def stdout = new ByteArrayOutputStream()
+        String tagIsh
+        try {
+            exec {
+                commandLine 'git', 'describe', '--tags', '--exclude="Dev"'
+                standardOutput = stdout
+            }
+            tagIsh = stdout.toString().trim().toLowerCase()
+        } catch(Exception e) {
+            tagIsh = "dev-Unknown"
+        }
+        boolean isDev = tagIsh.matches(".*-[0-9]*-g[0-9a-f]*")
+        if(isDev) tagIsh = "dev-" + tagIsh
+        println("Picked up version: " + tagIsh)
+        return tagIsh
+    }
+    ext.versionString = getCurrentVersion()
+}
+
+task writeCurrentVersionJava {
+    String date = DateTimeFormatter.ofPattern("yyyy-M-d hh:mm:ss").format(LocalDateTime.now())
+    File versionFile = new File(Path.of("$projectDir", "src", "main", "java", "org", "photonvision", "PhotonVersion.java")
+            .toAbsolutePath().toString())
+    versionFile.delete()
+    versionFile << "package org.photonvision;\n" +
+            "\n" +
+            "/*\n" +
+            " * Autogenerated file! Do not manually edit this file. This version is regenerated\n" +
+            " * any time the publish task is run, or when this file is deleted.\n" +
+            " */\n" +
+            "\n" +
+            "@SuppressWarnings(\"ALL\")\n" +
+            "public final class PhotonVersion {\n" +
+            "    public static final String versionString = \"${versionString}\";\n" +
+            "    public static final String buildDate = \"${date}\";\n" +
+            "    public static final boolean isRelease = !versionString.startsWith(\"dev\");\n" +
+            "}"
+}
+
+build.dependsOn writeCurrentVersionJava