Fix plugin validation

IntelliJ didn't save these files so it wasn't picked up by lazygit :P

`validatePlugins` ensures the proper usage of task annotations, and it
seems like I misused Gradle's `@Internal` annotation for these
properties.

Author: Jonathing

src/main/groovy/net/minecraftforge/gradleutils/shared/EnhancedTask.java

@@ -49,7 +49,6 @@ default Provider<RegularFile> getDefaultOutputFile() {
     ///
     /// @param ext The extension to use for the file
     /// @return A provider for the file
-    @Internal
     default Provider<RegularFile> getDefaultOutputFile(String ext) {
         return this.getPlugin().getLocalCaches().file("%s/output.%s".formatted(this.getName(), ext)).map(this.getPlugin().getProblemsInternal().ensureFileLocation());
     }

src/main/groovy/net/minecraftforge/gradleutils/shared/ToolExecBase.java

@@ -29,7 +29,7 @@
 public abstract class ToolExecBase<P extends EnhancedProblems> extends JavaExec {
     private final P problems;
     /// The default tool directory (usage is not required).
-    protected final @Internal DirectoryProperty defaultToolDir;
+    protected final DirectoryProperty defaultToolDir;
 
     /**
      * @see <a href="https://docs.gradle.org/current/userguide/service_injection.html#sec:projectlayout">ProjectLayout