feat(reaction_contribution_dashboard): added small web app to explore reaction contributions over time

This is a static webpage which will view JSON files in a format which I use (and will build into GridFire) and let users investigate the contributions each reaction at each timestep makes to the overall abundance of each species. This is invaluable when debugging a newtowk

BREAKING CHANGE:

utils/app/reaction_contributions/readme.md

@@ -0,0 +1,20 @@
+# Reaction Contribution Web App
+This small static web app allows you to load up a reactions contributions JSON file and visualize the contributions of different reactions to different species. This is useful for debugging.
+
+The JSON file must have the schema
+
+```json
+{
+  i: {
+     t: float,
+     dt: float,
+     reaction_contribution: {
+        Species: {
+           reaction: float
+        }
+     }
+  }
+}
+
+```
+where i counts from 0 -> the number of timesteps, Species is the species name (so if at one timestep there are 10 species tracked there will be 10 species entries), and reaction is the projectile-ejectile name of a reaction.