fix(swagger): Query Enums with isArray and enumName have type 'array' in schema

[arkraft]

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• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

I have a reproduction repository: https://github.com/arkraft/enum-array-repro

If a define a query like this:

enum LettersEnum {
  A = 'a',
  B = 'b',
  C = 'c',
}

@ApiQuery({
    name: 'letters',
    enum: LettersEnum,
    enumName: 'LettersEnum',
    isArray: true,
  })
  getHello(@Query('letters') letters: LettersEnum[]): string {

the final array should be of type string and the query param should be of type array. Instead, both of them are strings:

"components": {
        "schemas": {
            "LettersEnum": {
                "type": "array",
                "enum": [
                    "a",
                    "b",
                    "c"
                ]
            }
        }
    }

What is the new behavior?

With this PR, the extracted enum will have the correct enum type

"components": {
        "schemas": {
            "LettersEnum": {
                "type": "string",
                "enum": [
                    "a",
                    "b",
                    "c"
                ]
            }
        }
    }

Does this PR introduce a breaking change?

• Yes
• No

Other information

I edited the enum tests to include the @Query' and '@Param in the request itself, because I believe, this is the correct use case for them. I would also revert the change, if it is not wanted

[kamilmysliwiec]

lgtm