[API] Add a mechanism for Dear ImGui assertion callbacks (#100)

* Syncing wip to github

* Assertion callback works

* Restore example that does not crash

* Add comment in build script. Merge with upstream.

* Fix assert always triggering

* Resolve jvm env at runtime to prevent looking up bad stack address

* Fixed EXCEPTION_ACCESS_VIOLATION within native code after callback was complete.

* Fix linting errors

* Change ImGui to Dear ImGui

Co-authored-by: SpaiR <klimbetoo@gmail.com>

* Move jvm native layer to its own header/source

Co-authored-by: SpaiR <klimbetoo@gmail.com>

buildSrc/src/main/groovy/tool/generator/GenerateLibs.groovy

@@ -4,6 +4,7 @@ import com.badlogic.gdx.jnigen.*
 import groovy.transform.CompileStatic
 import org.gradle.api.DefaultTask
 import org.gradle.api.file.CopySpec
+import org.gradle.api.file.DuplicatesStrategy
 import org.gradle.api.tasks.Internal
 import org.gradle.api.tasks.TaskAction
 
@@ -53,6 +54,13 @@ class GenerateLibs extends DefaultTask {
             }
             spec.from(project.rootProject.file('imgui-binding/src/main/native'))
             spec.into(jniDir)
+            spec.duplicatesStrategy = DuplicatesStrategy.INCLUDE //Allows for duplicate imconfig.h, we ensure the correct one is copied below
+        }
+
+        //Ensure we overwrite imconfig.h with our own
+        project.copy { CopySpec spec ->
+            spec.from(project.rootProject.file('imgui-binding/src/main/native/imconfig.h'))
+            spec.into(jniDir)
         }
 
         //Copy dirent for ImGuiFileDialog