Move stubs from ./stubs to ./shared/Stubs

Gathers all shared test code in single place.

tests/unit/shared/Stubs/ProcessEnvironmentStub.ts

@@ -0,0 +1,8 @@
+export function getProcessEnvironmentStub(): NodeJS.ProcessEnv {
+  return {
+    VUE_APP_VERSION: 'stub-version',
+    VUE_APP_NAME: 'stub-name',
+    VUE_APP_REPOSITORY_URL: 'stub-repository-url',
+    VUE_APP_HOMEPAGE_URL: 'stub-homepage-url',
+  };
+}