[typescript-angular] Incorrect handling of model-name-prefix and model-name-suffix

Description

When the --model-name-prefix or --model-name-suffix are used, the model filename
includes the prefix/suffix, but the import filename includes them twice.

For example, if we use "--model-name-prefix swg" and the model is "pet", the resulting
model filename is "SwgPet.ts", but corresponding import is:

import { SwgSwgPet} from '../model/SwgSwgPet';

Swagger-codegen version

ref: refs/heads/master

Swagger declaration file content or url

Command line used for generation

Steps to reproduce

java -jar swagger-codegen-cli.jar generate -l typescript-angular --model-name-prefix swg

Related issues/PRs

#7865

Suggest a fix/enhancement