[PS 920] Fix selfhosted url validations

[LRNcardozoWDF]

Type of change

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

Objective

Added feedback to user when saving a bad formed URL in Settings page or trying to perform login with a previously saved bad formed url.

Code changes

• src/App/Pages/Accounts/EnvironmentPage.xaml: Refactor to use AsyncCommand;
• src/App/Pages/Accounts/EnvironmentPage.xaml.cs: Since AsyncCommand has proper validation to ensure multiple clicks aren't allowed I removed this validation;
• src/App/Pages/Accounts/EnvironmentPageViewModel.cs: Added validation for URLs saved and show pop up with error message;
• src/App/Resources/AppResources.resx: Added string with error message for when user tries to save a bad formed URL;
• src/Core/Services/ApiService.cs: Added validation for bad formed URL previously saved in Settings and show pop up with error. (Note: Since Bit.Core doesn't have access to src/App/Resources/AppResources.resx the message is hard coded for now).

Screenshots

Before you submit

• 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)

[fedemkr]

A couple of things to improve and on the PR:

• Change the title to [PS-920] Fix environment url validations so the format is alike the other PRs.
• On the description, I'd clarify that Settings page is the environment's one or it could be misleading to the Settings tab in the app's home.

[fedemkr]

Good work, just one thing I forgot to mention on the first review, and even though the method didn't have exception handling before, we should add it.