provide a way to check PD RPC client specific error class, or always retry

[lance6716]

Enhancement Task

There are some special error types like violation of WithOutputMustContainAllKeyRange. PD client should provide a function to let caller identify them quickly, rather than

https://github.com/tikv/pd/blob/e8c05e0e28e39e345b26f23de237879a90f9a752/client/client.go#L1715-L1725

Or it's better that PD client internally retry for these errors, because callers will retry anyway.