R echo client tests (#17629)

* add r echo api client sample

* add r workflow

* fix

* add env

* set r version

* install curl

* install dep

* fix

* comment out installation

samples/client/echo_api/r/.openapi-generator/FILES

@@ -0,0 +1,46 @@
+.Rbuildignore
+.github/workflows/r-client.yaml
+.gitignore
+.lintr
+.travis.yml
+DESCRIPTION
+NAMESPACE
+R/api_client.R
+R/api_response.R
+R/auth_api.R
+R/bird.R
+R/body_api.R
+R/category.R
+R/data_query.R
+R/default_value.R
+R/form_api.R
+R/header_api.R
+R/number_properties_only.R
+R/path_api.R
+R/pet.R
+R/query.R
+R/query_api.R
+R/string_enum_ref.R
+R/tag.R
+R/test_query_style_deep_object_explode_true_object_all_of_query_object_parameter.R
+R/test_query_style_form_explode_true_array_string_query_object_parameter.R
+README.md
+docs/AuthApi.md
+docs/Bird.md
+docs/BodyApi.md
+docs/Category.md
+docs/DataQuery.md
+docs/DefaultValue.md
+docs/FormApi.md
+docs/HeaderApi.md
+docs/NumberPropertiesOnly.md
+docs/PathApi.md
+docs/Pet.md
+docs/Query.md
+docs/QueryApi.md
+docs/StringEnumRef.md
+docs/Tag.md
+docs/TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter.md
+docs/TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter.md
+git_push.sh
+tests/testthat.R

samples/client/echo_api/r/.openapi-generator/VERSION

@@ -0,0 +1 @@
+7.3.0-SNAPSHOT