[BUG] [typescript-axios] parameter with date format has incorrect types

Description

If a date format is specified for a parameter, the generated code for axios will include the following:

      if (fromDate !== undefined) {
        localVarQueryParameter['fromDate'] =
          (fromDate as any) instanceof Date
            ? (fromDate as any).toISOString().substr(0, 10)
            : fromDate;
      }

However, the type for that argument in the generated method is fromDate?: string, which prevent us from actually passing a Date instance.

Either we remove that code, or change the type definition to be fromDate?: string | Date

openapi-generator version

4.3.1

OpenAPI declaration file content or url

     parameters:
        - in: query
          name: fromDate
          schema:
            type: string
            format: date

Command line used for generation

openapi-generator \
        generate \
        -g typescript-axios \
        -i "../external-api/$name.yaml" \
        -o "generated-src/$name"

Start with the typescript-axios generator and reproduce the provided OpenAPI declaration and generation command. Inspect the generated method signature and query-parameter handling for a date-formatted parameter. Done means the generated TypeScript type and runtime date handling agree, with the generated output matching the intended behavior.