Move Log4j plugins to own source set (#9428)

patches/server/0155-Handle-plugin-prefixes-using-Log4J-configuration.patch

@@ -15,18 +15,18 @@ This may cause additional prefixes to be disabled for plugins bypassing
 the plugin logger.
 
 diff --git a/build.gradle.kts b/build.gradle.kts
-index ab46f9cb3bb94af0c418a5d39f2f63a6d3a0e07c..a06b75a78ab96229a6e9b97de913df9050325c04 100644
+index 4e682e084a7f653ccb90756bab884499861f9060..9013a7218ddf3919e5cddd745d03c73d1b6480ae 100644
 --- a/build.gradle.kts
 +++ b/build.gradle.kts
-@@ -19,7 +19,7 @@ dependencies {
+@@ -25,7 +25,7 @@ dependencies {
            all its classes to check if they are plugins.
            Scanning takes about 1-2 seconds so adding this speeds up the server start.
       */
--    runtimeOnly("org.apache.logging.log4j:log4j-core:2.14.1")
-+    implementation("org.apache.logging.log4j:log4j-core:2.14.1") // Paper - implementation
-     annotationProcessor("org.apache.logging.log4j:log4j-core:2.14.1") // Paper - Needed to generate meta for our Log4j plugins
-     // Paper end
-     implementation("org.apache.logging.log4j:log4j-iostreams:2.19.0") // Paper - remove exclusion
+-    runtimeOnly("org.apache.logging.log4j:log4j-core:2.19.0")
++    implementation("org.apache.logging.log4j:log4j-core:2.19.0") // Paper - implementation
+     log4jPlugins.annotationProcessorConfigurationName("org.apache.logging.log4j:log4j-core:2.19.0") // Paper - Needed to generate meta for our Log4j plugins
+     runtimeOnly(log4jPlugins.output)
+     alsoShade(log4jPlugins.output)
 diff --git a/src/main/java/org/spigotmc/SpigotConfig.java b/src/main/java/org/spigotmc/SpigotConfig.java
 index 0a0aa6de31a94a701074cc5f43c94be7515a185c..489ce6f439778b26eb33ede9432681d4bf9e0116 100644
 --- a/src/main/java/org/spigotmc/SpigotConfig.java