Methodology page update for Score L (#1010)

* Add first column of Methodology score L

- create a new component MethodologyFormula (MF)
- MF component contain text on formula calculation
- add snapshots

* Add 2nd column to Methodology page

- add LowIncome component
- add USWDS styles on download component
- add margin-top styles to global
- enable all font-sizes to theme file

* Add Categories to Methodology page

- create CategoryCard component
- create Categories component
- add snapshots

* Update datasets

- update styling to match mock
- add additional indicators
- remove additional indicators
- update snapshots

* Add links to categories to datasets

- update snapshots

* Remove additional indicator test as they now N/A

* ensure each DOM ID is unique for a11y

- update snapshots

* Add Category heading for a11y

- removes ScoreSteps tests
- comment out ScoreStep component
- update snapshots
- cypress passes all a11y

* Update to methodology copy

- based on PDF and spreadsheet and Living Copy
-updates snapshots

* Add comments around using IF, AND, ELSE constants

- make indicator constant names more explicit

* Update copy based on living doc

- update snapshots

client/src/components/DatasetCard/tests/__snapshots__/datasetCard.test.tsx.snap

@@ -1,41 +1,43 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`rendering of addtional indicator dataset card checks if component renders 1`] = `<DocumentFragment />`;
-
 exports[`rendering of indicator dataset card checks if component renders 1`] = `
 <DocumentFragment>
-  <div>
+  <div
+    id="low-income"
+  >
     <h3>
-      Area Median Income
+      Low Income
     </h3>
     <div>
-      Median income of the census block group calculated as a percent 
-    of the metropolitan area’s or state's median income.
+      
+    Percent of a block group's population in households where household income is at or below
+    200% of the federal poverty level.
+    
     </div>
     <ul>
       <li>
         <span>
-          Data source: 
+          Responsible Party: 
         </span>
         <a
           href="https://www.census.gov/programs-surveys/acs"
           rel="noreferrer"
           target="_blank"
         >
-          Census's American Community Survey
+          Census's American Community Survey.
         </a>
       </li>
       <li>
         <span>
-          Data resolution: 
+          Date range: 
         </span>
-        Census block group
+        2015-2019
       </li>
       <li>
         <span>
-          Data date range: 
+          Used in: 
         </span>
-        2015-2019
+        All methodologies except for training and workforce development
       </li>
     </ul>
   </div>