Blazor Identity scaffolder should generate a DbContext with a unique name

[danroth27]

If I use the Blazor Identity scaffolder to generate an IdentityDbContext type it doesn't seem to detect if a type already exists with the suggested default name. You then get the following error when running the Blazor Identity scaffolder:

I hit this when I run the Blazor Identity scaffolder after running the Blazor CRUD scaffolder, which uses the same default suggested name for the generated DbContext.

Repro steps:

• Create a Blazor Web App
• Run the Blazor CRUD scaffolder and generate a DbContext using the default name
• Run the Blazor Identity scaffodler and generate an IdentityDbContext using the default name

Actual result: Error complaining that the DbContext isn't an IdentityDbContext
Expected result: The suggested name for the IdentityDbContext is unique