[Workspace] Consume workspace in saved objects client.

[SuZhou-Joe]

Is your feature request related to a problem? Please describe.

Workspace will be a concept to manage saved objects, therefore we need to make saved objects client(public side) be aware of what current workspace is and bypass the worksapce params to server side.

Describe the solution you'd like

Add current workspace a private property of savedObjectsClient and expose a interface to change the property if user switches the workspace. And there may be some cases that user may want to overwrite the default workspace behavior so the client should honor the workspaces params in the input of each method call.

Describe alternatives you've considered

N/A

Additional context

Add any other context or screenshots about the feature request here.

[SuZhou-Joe]

#4944