[BUG] swift5 generator does not support Content-Type with appended charset

Created by: Jonas1893

Bug Report Checklist

Have you provided a full/minimal spec to reproduce the issue?
Have you validated the input using an OpenAPI validator (example)?
Have you tested with the latest master to confirm the issue still exists?
Have you searched for related issues/PRs?
What's the actual output vs expected output?
[Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

If a spec defines a content-type with an appended charset, generated client currently crashes as we are running into the fatalError because we are testing for equality and not for contains in Alamofire*/URLSessionImplementations.swift

openapi-generator version

6.2.1 and earlier

OpenAPI declaration file content or url

Consider any request that appends a charset to a content-type, either in the request header or request body like e.g. so:

requestBody:
        content:
          application/x-www-form-urlencoded; charset=utf-8:

Generation Details

Steps to reproduce

Use petstore-with-deprecated-fields.yaml and modify requestBody of post '/pet/{petId}' to use application/x-www-form-urlencoded; charset=utf-8 like described here

Using this API will now lead to a crash

Related issues/PRs

Suggest a fix

For content-type checks (where we fall through to fatalError) we should not check for equality but rather for contains or hasPrefix. I'll open a PR for it for easier discussion