Codegen: 7f Generate application index/home page

[mat-app]

Dependencies

1. This issue is dependent on Codegen: Create templates for application index page #103

Description

Goal of this story is to generate application index page which will contains menu for generated entities.
This page will be generated from template.

Proposed Solution

• add generateAppIndexPage(template) to AppGenerator
• this function will generate application index page according to selected ui framework
• pick template according to ui library and replace everything what is needed
• extend generatePages() with calling of this new method and save this file as index.tsx
• we also have to include translate messages definitions (generated files by Codegen: 7e. Generate translations #101) and use them in format provider like here
  https://github.com/iteria-app/example-material-ui/blob/622f17a1288c83814a58d7ce9c56fc4e2e0204f7/src/App.tsx#L15 and https://github.com/iteria-app/example-material-ui/blob/622f17a1288c83814a58d7ce9c56fc4e2e0204f7/src/index.tsx#L16 and here for grommet https://github.com/iteria-app/example-grommet/blob/4c4a39c955566899c1f2f2eb46e42f9c22e62f24/src/index.tsx#L44
• we need to use generated routes here for building menu (generating routes will be done here Codegen: 7c Generate routes (ETA 27.6.2021) #91)
• menu items for entities will be pluralized
• text of menu item is localized message

Acceptance criteria

• GIVEN choose to generate Customer and Product
  WHEN i run generatePages()
  THEN application index page will be generated and will contains menu item for Customers and Products

[jozef-slezak]

We need #117 first - addMenuItem() (see https://app.diagrams.net/#G173Xc2ZPGThGWlei9SPGh6IQfGnaYiefc)