[API] ListReleases add filter for draft and pre-releases (#16175)

* invent ctx.QueryOptionalBool

* [API] ListReleases add draft and pre-release filter

* Add X-Total-Count header

* Add a release to fixtures

* Add TEST for API ListReleases

integrations/api_repo_test.go

@@ -223,7 +223,7 @@ func TestAPIViewRepo(t *testing.T) {
 	DecodeJSON(t, resp, &repo)
 	assert.EqualValues(t, 1, repo.ID)
 	assert.EqualValues(t, "repo1", repo.Name)
-	assert.EqualValues(t, 2, repo.Releases)
+	assert.EqualValues(t, 3, repo.Releases)
 	assert.EqualValues(t, 1, repo.OpenIssues)
 	assert.EqualValues(t, 3, repo.OpenPulls)