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/LowIncome/LowIncome.test.tsx

@@ -0,0 +1,16 @@
+import * as React from 'react';
+import {render} from '@testing-library/react';
+import {LocalizedComponent} from '../../test/testHelpers';
+import LowIncome from './LowIncome';
+
+describe('rendering of the LowIncome', () => {
+  const {asFragment} = render(
+      <LocalizedComponent>
+        <LowIncome />
+      </LocalizedComponent>,
+  );
+
+  it('checks if component renders', () => {
+    expect(asFragment()).toMatchSnapshot();
+  });
+});