Change subtitle heading to new slogan

- Unify reading subtitle/slogan throughout the application.
- Refactor related unit tests for easier future changes.
- Add typed constants for Vue app environment variables.

src/application/Parser/ProjectInformationParser.ts

@@ -3,13 +3,26 @@ import { ProjectInformation } from '@/domain/ProjectInformation';
 import { Version } from '@/domain/Version';
 
 export function parseProjectInformation(
-  environment: NodeJS.ProcessEnv,
+  environment: NodeJS.ProcessEnv | VueAppEnvironment,
 ): IProjectInformation {
-  const version = new Version(environment.VUE_APP_VERSION);
+  const version = new Version(environment[VueAppEnvironmentKeys.VUE_APP_VERSION]);
   return new ProjectInformation(
-    environment.VUE_APP_NAME,
+    environment[VueAppEnvironmentKeys.VUE_APP_NAME],
     version,
-    environment.VUE_APP_REPOSITORY_URL,
-    environment.VUE_APP_HOMEPAGE_URL,
+    environment[VueAppEnvironmentKeys.VUE_APP_SLOGAN],
+    environment[VueAppEnvironmentKeys.VUE_APP_REPOSITORY_URL],
+    environment[VueAppEnvironmentKeys.VUE_APP_HOMEPAGE_URL],
   );
 }
+
+export const VueAppEnvironmentKeys = {
+  VUE_APP_VERSION: 'VUE_APP_VERSION',
+  VUE_APP_NAME: 'VUE_APP_NAME',
+  VUE_APP_SLOGAN: 'VUE_APP_SLOGAN',
+  VUE_APP_REPOSITORY_URL: 'VUE_APP_REPOSITORY_URL',
+  VUE_APP_HOMEPAGE_URL: 'VUE_APP_HOMEPAGE_URL',
+} as const;
+
+export type VueAppEnvironment = {
+  [K in keyof typeof VueAppEnvironmentKeys]: string;
+};