fix(CRATemplate): Fix lint command

ESLint was broken in the CRA template for two reasons:

- ESLint was unable not import `eslint-config-prettier` (dependency of `@defencedigital/eslint-config-react`) – could be to do with package hoisting not too clear why just this one specifically (is mentioned here though: prettier/eslint-plugin-prettier#396)
- it was trying to lint `src/*` which would be expanded by the shell and fail if the `src/components` directory was empty (except for `.gitkeep`)

This fixes both of those problems, and adds a step to the smoke test workflow to explicitly test the lint command.

.github/workflows/npmsmoketest.yml

@@ -59,3 +59,8 @@ jobs:
  cd $RUNNER_TEMP/my-app
  grep version node_modules/@defencedigital/**/package.json
  yarn build
+
+ - name: Lint boilerlate app
+ run: |
+ cd $RUNNER_TEMP/my-app
+ yarn lint

packages/cra-template-defencedigital/template.json

@@ -3,7 +3,7 @@
  "author": "Defence Digital",
  "scripts": {
  "codegen": "gql-gen --config codegen.yml",
- "lint": "eslint src/* --ext .ts --ext .tsx"
+ "lint": "eslint src --ext .ts --ext .tsx"
  },
  "dependencies": {
  "styled-components": "^5.2.1",
@@ -20,6 +20,7 @@
  "@testing-library/jest-dom": "^5.5.0",
  "@testing-library/react": "^10.0.4",
  "@testing-library/user-event": "^10.1.0",
+ "eslint-plugin-prettier": "^4.0.0",
  "formik": "^2.2.9",
  "jest-canvas-mock": "^2.3.0",
  "typescript": "^3.8.0",