Import project: Support repository URLs with .git or / suffix

[viennem]

Describe the bug

When importing a project, the repository URL should support URLs with .git or / at the end.

This issue applies to both "Import new project" and "Create a project from a template" dialogs.

Currently:

• .git suffix is not accepted by the validation rule:
  
  It should be accepted, because many users are used to copy/paste the URL from GitHub's "Code" button.

• / suffix is accepted by the validation rule, but the project name extracted from the URL is empty, and it causes an error 404 after importing the project.
  
  The router redirected me to this URL: http://localhost:8080/projects//models.

Application

• leto-modelizer commit hash: f59e63e9d861fb5d0f0849dc7983be3a76bd779a.