paquo.jpype_backend: set java.library.path to appdir

This adds java.library.path = {qupath_app_dir} to the jvm options:
- allows openslide to be used by qupath java libraries
- improves add_image speed for tif-files

Partially reverts: d7df792
Relates to: #20

paquo/jpype_backend.py

@@ -126,9 +126,10 @@ def qupath_jvm_info_from_qupath_dir(qupath_dir: Path, jvm_options: List[str]) ->
     if not (app_dir.is_dir() and runtime_dir.is_dir() and jvm_dir.is_file()):
         raise FileNotFoundError('qupath installation is incompatible')
 
-    # note: jvm_options is just passed through
-    #   but this is the best place to have os-specific jvm_options modifications
-    #   in case it's needed at some point
+    # Add java.library.path so that the qupath provided openslide works
+    jvm_options.append(f"-Djava.library.path={app_dir}")
+    jvm_options = list(dict.fromkeys(jvm_options))  # keep options unique and in order
+
     return app_dir, runtime_dir, jvm_dir, jvm_options