Admin page to update server status

[ikhoon]

• A server's executor status can be updated only via the REST API in ServerStatusService.
  

  centraldogma/server/src/main/java/com/linecorp/centraldogma/server/internal/api/sysadmin/ServerStatusService.java

  Lines 58 to 67 in c2d559d

  	* <p>Patches the server status with a JSON patch. Currently used only for entering read-only.
  	*
  	* <p>If {@link UpdateServerStatusRequest#scope()} is omitted, defaults to {@link Scope#ALL}.
  	* If the scope is {@link Scope#ALL}, the new status is propagated to all cluster servers.
  	* If the scope is {@link Scope#LOCAL}, the new status is only applied to the current server.
  	*/
  	@Put("/status")
  	@Consumes("application/json")
  	@RequiresSystemAdministrator
  	public CompletableFuture<ServerStatus> updateStatus(UpdateServerStatusRequest statusRequest)

• A server's health can't be updated externally.
  

  centraldogma/server/src/main/java/com/linecorp/centraldogma/server/CentralDogma.java

  Line 235 in 3d08000

  private final SettableHealthChecker serverHealth = new SettableHealthChecker(false);

If an admin page is provided to manage the statuses, administrators can easily monitor and quickly update the statuses, saving time on operations.

centraldogma/webapp/src/pages/app/settings/index.tsx

Line 20 in efb85f5

const SystemSettingsPage = () => {

[minwoox]

That's going to be very useful. 👍