Added support for cookie parameters to the jaxrs-spec generator, which should fix #2908.
Added the test case testGenerateApiWithCookieParameter_issue2908 to JavaJAXRSSpecServerCodegenTest.java, which uses the file issue_2908.yaml for testing that cookie parameter generation works.
Briefly, the fix was adding a new mustache template (cookieParams.mustache) to the jaxrs-spec generator and referencing it in api.mustache in the same way the other parameter types are referenced (e.g. queryParams.mustache).
The new cookieParams.mustache is essentially a copy of the queryParams.mustache.

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cc @bbdouglas (2017/07) @sreeshas (2017/08) @jfiala (2017/08) @lukoyanov (2017/09) @cbornet (2017/09) @jeff9finger (2018/01) @karismann (2019/03) @Zomzog (2019/04) @lwlee2608 (2019/10) @bkabrda (2020/01)