Simplify code and improve TenantID and UserRole handling

[tjementum]

Summary & Motivation

Several small updates to simplify code and improve functionality related to TenantID and UserRole.

• Rename User.UserRole to Role, and change UserRole.TenantUser/TenantAdmin/TenantOwner to Member/Admin/Owner. The UserRole enum has been updated for simplicity in the front end, with UserRole.User renamed to UserRole.Member, aligning with common SaaS conventions.
• Allow hyphens in TenantID. Previously, TenantID only allowed a-z0-9. Hyphens are now allowed but not as the first or last character.
• Simplify getting the path to the WebApp/dist folder by changing from a DI service resolution to a static property.
• Remove support for abstract fluent validation to simplify code. Previously, service registration was complex to support abstract Fluent Validation classes. This support has been removed, simplifying the registration to services.AddValidatorsFromAssembly(...);.

Checklist

• [x] I have added a Label to the pull-request
• [x] I have added tests, and done manual regression tests
• [x] I have updated the documentation, if necessary

[sonarcloud[bot]]

Quality Gate failed

Failed conditions
10.6% Duplication on New Code (required ≤ 3%)

See analysis details on SonarCloud