Simplify HTML for an investment row

Since we define the `data-field` element, we can style each element
individually with CSS.

I'm not sure whether these styles make sense, though. For instance, why
is "Supports" aligned to the center, since it's a number? For now, we're
leaving it as it was.

app/assets/stylesheets/admin/budget_investments/investments.scss

@@ -0,0 +1,15 @@
+.admin .admin-budget-investments {
+  td {
+    &[data-field=supports],
+    &[data-field=valuation_finished],
+    &[data-field=visible_to_valuators],
+    &[data-field=selected],
+    &[data-field=incompatible] {
+      text-align: center;
+    }
+
+    &:not([data-field=id], [data-field=title], [data-field=supports]) {
+      font-size: $small-font-size;
+    }
+  }
+}