Update cell-numeric-superscript.csl (#6188)

via https://forums.zotero.org/discussion/99081/add-doi#latest

It looks like Cell generally has added DOIs now as it appears in the guidelines of OP's style, but also in the guidelines we based our style on:
https://www.cell.com/current-biology/authors
https://www.cell.com/chem/authors

Author: POBrien333

cell-numeric-superscript.csl

@@ -36,13 +36,12 @@
   </macro>
   <macro name="access">
     <choose>
-      <if variable="URL">
-        <choose>
-          <if type="webpage dataset entry-dictionary entry-encyclopedia post post-weblog" match="any">
-            <text variable="URL"/>
-          </if>
-        </choose>
+      <if match="any" variable="DOI">
+        <text variable="DOI"/>
       </if>
+      <else-if match="any" type="webpage dataset entry-dictionary entry-encyclopedia post post-weblog">
+        <text variable="URL"/>
+      </else-if>
     </choose>
   </macro>
   <macro name="title">

cell-numeric.csl

@@ -37,18 +37,12 @@
   </macro>
   <macro name="access">
     <choose>
-      <if variable="URL">
-        <text value="Available at:" suffix=" "/>
-        <text variable="URL"/>
-        <group prefix=" [" suffix="]">
-          <text term="accessed" text-case="capitalize-first" suffix=" "/>
-          <date variable="accessed">
-            <date-part name="month" suffix=" "/>
-            <date-part name="day" suffix=", "/>
-            <date-part name="year"/>
-          </date>
-        </group>
+      <if variable="DOI">
+        <text variable="DOI"/>
       </if>
+      <else-if match="any" type="webpage dataset entry-dictionary entry-encyclopedia post post-weblog">
+        <text variable="URL"/>
+      </else-if>
     </choose>
   </macro>
   <macro name="title">