Fix list response keys derived from the API name (#162)

CloudStack keys a list response's items by the response object name, not by the
API name the generator derived the tag from, so 16 list APIs decoded as a
permanently empty slice while count parsed from the same body and no error was
returned. The keys are now data in a documented listResponseKeys map rather than
24 hand-written switch arms, each one observed on a real server and pinned by a
test, leaving only genuine shape differences in the switch; listCaCertificate and
listUsageServerMetrics also become pointers, since they return a single object
with no count. Also moves the getRawValue empty-array guard from #154 into the
generator, where it had been edited into the generated file only and so was
reverted by every `make code`.

SDK for Apache CloudStack 4.22.0 APIs

Fix CNI Configuration as it internally uses UserData (#125)

Update listApis with 4.21.0 APIs (#120)

* Update listApis with 4.21 APIs

* add template_id to required params for backward compatability

* Add support for GPU apis (#121)

* Add support to Cni config, Nsx, Netris service management and add additional k8s APIs support (#123)

* Add support for extension APIs (#124)

* Add support for backup & recovery service (#122)

* Add support for backup & recovery service

* add additional apis to the vm service

Update counter, condition and autoscale policies type in responses (#119

)

Support for Apache CloudStack 4.20.1 APIs

Add test data for register userkeys (#99)

* Add test data for register userkeys

* add newline

update generated files

Merge pull request #86 from apache/post

Use POST for user sensitive calls

Restore methods with optional params for 4.19 compatability (#80)

Add optional params from #77 to the requiredParams.go.