[rust-server] support multiple tags

Created by: bjgill

Description

See https://github.com/swagger-api/swagger-codegen/issues/8201#issuecomment-389895761 - rust-server cannot cope with the following endpoint:

  /fake/many_tags:
    get:
      tags:
        - user
        - store
      description: Multiple status values can be provided with comma separated strings
      responses:
        '200':
          description: foo

As far as I can tell, this causes rust-server to generate multiple trait methods with the same name.

We should fix this and add a test.

(Note: this part of a set of issues from swagger-codegen. I didn't fix this as part of the move to openapi-generator. Thus I strongly suspect rust-server in openapi-generator also suffers the same problem. I'm not planning on working on this at the moment - contributions gratefully welcomed)

openapi-generator version

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Command line used for generation

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