[M][REQ][JAVA]: Add option to generate arrays with "uniqueItems" true as Sets rather than Lists (#5466)

* [REQ][JAVA]: Add option to generate arrays with "uniqueItems" true as Sets rather than Lists
 - Update Java code generation to use sets instead of lists when uniqueItems is set to true
 - Add import resolution for sets
 - Add tests and fix broke tests

resolve #5254

* Update Javascript, Perl, Python and Ruby to preserve current functionality.

* Switch set implementation to LinkedHashSet

* Fix missing import for uniqueItems used on param.

* Fix missing import and return type for responses with uniqueItems

* Fix default values for array of enum

* Update generated samples

* fix merge issue

* Update generated samples

Co-authored-by: William Cheng <wing328hk@gmail.com>

samples/client/petstore/java/resttemplate-withXml/api/openapi.yaml

@@ -144,6 +144,7 @@ paths:
           items:
             type: string
           type: array
+          uniqueItems: true
         style: form
       responses:
         "200":
@@ -153,11 +154,13 @@ paths:
                 items:
                   $ref: '#/components/schemas/Pet'
                 type: array
+                uniqueItems: true
             application/json:
               schema:
                 items:
                   $ref: '#/components/schemas/Pet'
                 type: array
+                uniqueItems: true
           description: successful operation
         "400":
           content: {}
@@ -1384,6 +1387,7 @@ components:
           items:
             type: string
           type: array
+          uniqueItems: true
           xml:
             name: photoUrl
             wrapped: true