Convert a few manual tests to unit tests (#1570)

* Towards #1290 automate some bullet examples into unit tests.

* Towards #1290 automate one core issue regression test

* Towards #1290 Automate a few more tests/examples

* resolve commit conflicts in 2 build.gradle files

Co-authored-by: Stephen Gold <[email protected]>

Author: MeFisto94

jme3-core/build.gradle

@@ -16,8 +16,7 @@ sourceSets {
 }
 
 dependencies {
-    testImplementation project(':jme3-testdata')
-    testImplementation project(':jme3-testdata')
+    testRuntime project(':jme3-testdata')
     testImplementation project(':jme3-desktop')
     testRuntime project(':jme3-plugins')
 }