[SG-223] Mobile username generator

[LRNcardozoWDF]

Type of change

• [ ] Bug fix
• [X] New feature development
• [ ] Tech debt (refactoring, code cleanup, dependency upgrades, etc)
• [ ] Build/deploy pipeline (DevOps)
• [ ] Other

Objective

Add username's generation option to mobile app.

Code changes

• GeneratorPage.xaml: Added UI elements needed for username generation options. Refactored password's display and some tags to help distinguish from password and username.
• GeneratorPage.xaml.cs: Added flags to control visual display of Password vs Username. Refactored Regenerate_Clicked into AsyncCommand in ViewModel.
• GeneratorPageViewModel.cs: Added logic to handle username creation, saving and loading username options. Refactored some properties to help distinguish from password and username.
• CipherAddEditPage.xaml: Refactored username field to grid and added button, with an icon, to navigate to Generator.
• CipherAddEditPageViewModel.cs: Added command to perform navigation to Generator page.
• AppResources.Designer.cs AppResources.resx: Added new strings.
• AppHelpers.cs: Added to new service to cache cleaning task.
• PickerIndexToBoolConverter.cs: Created to convert an int to boolean in order to control visibility of elements in xaml.
• Constants.cs: Added new constant key.
• ForwardedEmailServiceType.cs UsernameEmailType.cs UsernameType.cs: Added to help identify newly required types related to username creation.
• UsernameGenerationOptions.cs: Added model of username generation options.
• ApiService.cs: Added Http requests to various api's in order to consume their username creation service.
• StateService.cs: Added username generation options get/set support from/to storage.
• UsernameGenerationService.cs: Added to handle username creation based on username type intended.
• ServiceContainer.cs: Registered new service, UsernameGenerationService.cs.

Screenshots

Before you submit

• [X] I have checked for formatting errors (dotnet tool run dotnet-format --check) (required)
• [ ] I have added unit tests where it makes sense to do so (encouraged but not required)
• [ ] This change requires a documentation update (notify the documentation team)
• [ ] This change has particular deployment requirements (notify the DevOps team)