LPS-41309 Refactor to render error page on spi failure rather than triggering error processing logic

cc @mhan810

1) Create a class that impls SPIRegistryValidator from the console plugin
2) Register it into portal by calling SPIRegistryUtil.setSPIRegistryValidator(SPIRegistryValidator)
3) In the SPIRegistryValidator impl, when it sees the targeting spi is down, returns SPIRegistryUtil.getErrorSPI(), which does NOP on ACTION/EVENT/RESOURCE phases. On render phase, it simply outputs a message to say the spi is not unavailable, if necessary we may want to refine the message. See ErrorSPIAgent.service() render phase.