[Feature] Add Predict Pathway Page in Modern UI (#188)

## Major Changes
- Predict Pathway is now a separate view as it is meant as adavanced prediction interface

## Current status
![image.png](/attachments/c5bc3f5c-cf30-4b5f-acb3-a70117a96dae)

Co-authored-by: Tim Lorsbach <tim@lorsba.ch>
Reviewed-on: enviPath/enviPy#188
Co-authored-by: Tobias O <tobias.olenyi@envipath.com>
Co-committed-by: Tobias O <tobias.olenyi@envipath.com>

epdb/views.py

@@ -362,6 +362,18 @@ def index(request):
     return render(request, "index/index.html", context)
 
 
+def predict_pathway(request):
+    """Top-level predict pathway view using user's default package."""
+    if request.method != "GET":
+        return HttpResponseNotAllowed(["GET"])
+
+    context = get_base_context(request)
+    context["title"] = "enviPath - Predict Pathway"
+    context["meta"]["current_package"] = context["meta"]["user"].default_package
+
+    return render(request, "predict_pathway.html", context)
+
+
 def packages(request):
     current_user = _anonymous_or_real(request)
 
@@ -1301,7 +1313,7 @@ def package_compound_structures(request, package_uuid, compound_uuid):
 
     elif request.method == "POST":
         structure_name = request.POST.get("structure-name")
-        structure_smiles = request.POST.get("structure-smiles").strip()
+        structure_smiles = request.POST.get("structure-smiles")
         structure_description = request.POST.get("structure-description")
 
         try:
@@ -1483,11 +1495,11 @@ def package_rules(request, package_uuid):
 
         # Obtain parameters as required by rule type
         if rule_type == "SimpleAmbitRule":
-            params["smirks"] = request.POST.get("rule-smirks").strip()
+            params["smirks"] = request.POST.get("rule-smirks")
             params["reactant_filter_smarts"] = request.POST.get("rule-reactant-smarts")
             params["product_filter_smarts"] = request.POST.get("rule-product-smarts")
         elif rule_type == "SimpleRDKitRule":
-            params["reaction_smarts"] = request.POST.get("rule-reaction-smarts").strip()
+            params["reaction_smarts"] = request.POST.get("rule-reaction-smarts")
         elif rule_type == "ParallelRule":
             pass
         elif rule_type == "SequentialRule":
@@ -1684,7 +1696,7 @@ def package_reactions(request, package_uuid):
     elif request.method == "POST":
         reaction_name = request.POST.get("reaction-name")
         reaction_description = request.POST.get("reaction-description")
-        reactions_smirks = request.POST.get("reaction-smirks").strip()
+        reactions_smirks = request.POST.get("reaction-smirks")
         educts = reactions_smirks.split(">>")[0].split(".")
         products = reactions_smirks.split(">>")[1].split(".")