Implement role and user management enhancements

- Added MaxIpLimit to roles, allowing for the configuration of simultaneous IP limits for users.
- Updated role creation and update commands to include MaxIpLimit, ensuring proper handling in the application logic.
- Enhanced user management by introducing a DELETE endpoint for user accounts, with appropriate checks to prevent self-deletion.
- Updated documentation to reflect changes in role and user management, clarifying the new IP limit functionality and user deletion process.
- Adjusted related tests to cover new functionality and ensure robust validation of role and user management features.

backend/tests/PnvPanel.Application.Tests/Configs/GetMyConfigs/GetMyConfigsQueryHandlerTests.cs

@@ -1,6 +1,7 @@
 using NSubstitute;
 using PnvPanel.Application.Auth;
 using PnvPanel.Application.Common.Interfaces;
+using PnvPanel.Application.Common.Models;
 using PnvPanel.Application.Configs.GetMyConfigs;
 using PnvPanel.Application.Tests.TestSupport;
 using PnvPanel.Domain.Configs;
@@ -32,7 +33,7 @@ public class GetMyConfigsQueryHandlerTests
         dbContext.VpnConfigs.AddRange(activeConfig, revokedConfig, otherUsersConfig);
         await dbContext.SaveChangesAsync(CancellationToken.None);
 
-        var profile = new CurrentUserProfile(userId, "alice", Guid.NewGuid(), "user", true, false, 5, "sub-token");
+        var profile = new CurrentUserProfile(userId, "alice", Guid.NewGuid(), "user", true, false, 5, RoleQuota.Unlimited, "sub-token");
         _identityService.GetProfileAsync(userId, Arg.Any<CancellationToken>()).Returns(profile);
 
         var handler = new GetMyConfigsQueryHandler(dbContext, _identityService, FakeCurrentUser.Authenticated(userId));