[ruby] Support for per-operation servers (#7415)

* Support server configuration per operation

* regenerated+tests

* base_url fix

* support not templated urls

* revert update of ruby docs

samples/openapi3/client/features/dynamic-servers/ruby/spec/api/usage_api_spec.rb

@@ -0,0 +1,57 @@
+=begin
+#OpenAPI Extension with dynamic servers
+
+#This specification shows how to use dynamic servers.
+
+The version of the OpenAPI document: 1.0.0
+
+Generated by: https://openapi-generator.tech
+OpenAPI Generator version: 5.0.0-SNAPSHOT
+
+=end
+
+require 'spec_helper'
+require 'json'
+
+# Unit tests for DynamicServers::UsageApi
+# Automatically generated by openapi-generator (https://openapi-generator.tech)
+# Please update as you see appropriate
+describe 'UsageApi' do
+  before do
+    # run before each test
+    @api_instance = DynamicServers::UsageApi.new
+  end
+
+  after do
+    # run after each test
+  end
+
+  describe 'test an instance of UsageApi' do
+    it 'should create an instance of UsageApi' do
+      expect(@api_instance).to be_instance_of(DynamicServers::UsageApi)
+    end
+  end
+
+  # unit tests for custom_server
+  # Use custom server
+  # Use custom server
+  # @param [Hash] opts the optional parameters
+  # @return [Object]
+  describe 'custom_server test' do
+    it 'should work' do
+      # assertion here. ref: https://www.relishapp.com/rspec/rspec-expectations/docs/built-in-matchers
+    end
+  end
+
+  # unit tests for default_server
+  # Use default server
+  # Use default server
+  # @param [Hash] opts the optional parameters
+  # @return [Object]
+  describe 'default_server test' do
+    it 'should work' do
+      # assertion here. ref: https://www.relishapp.com/rspec/rspec-expectations/docs/built-in-matchers
+    end
+  end
+
+end