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/docs/PathApi.md

@@ -0,0 +1,62 @@
+# PathApi
+
+All URIs are relative to *http://localhost:3000*
+
+Method | HTTP request | Description
+------------- | ------------- | -------------
+[**TestsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPath**](PathApi.md#TestsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPath) | **GET** /path/string/{path_string}/integer/{path_integer}/{enum_nonref_string_path}/{enum_ref_string_path} | Test path parameter(s)
+
+
+# **TestsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPath**
+> character TestsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPath(path_string, path_integer, enum_nonref_string_path, enum_ref_string_path)
+
+Test path parameter(s)
+
+Test path parameter(s)
+
+### Example
+```R
+library(openapi)
+
+# Test path parameter(s)
+#
+# prepare function argument(s)
+var_path_string <- "path_string_example" # character | 
+var_path_integer <- 56 # integer | 
+var_enum_nonref_string_path <- "enum_nonref_string_path_example" # character | 
+var_enum_ref_string_path <- StringEnumRef$new() # StringEnumRef | 
+
+api_instance <- PathApi$new()
+# to save the result into a file, simply add the optional `data_file` parameter, e.g.
+# result <- api_instance$TestsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPath(var_path_string, var_path_integer, var_enum_nonref_string_path, var_enum_ref_string_pathdata_file = "result.txt")
+result <- api_instance$TestsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPath(var_path_string, var_path_integer, var_enum_nonref_string_path, var_enum_ref_string_path)
+dput(result)
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **path_string** | **character**|  | 
+ **path_integer** | **integer**|  | 
+ **enum_nonref_string_path** | Enum [success, failure, unclassified] |  | 
+ **enum_ref_string_path** | [**StringEnumRef**](.md)|  | 
+
+### Return type
+
+**character**
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: text/plain
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | Successful operation |  -  |
+