Reduce noise in logs

[ZakarFin]

• By default contexts in Tomcat are read-only. DatasourceHelper now detects this and prints out more helpful message in logs.
• Most users don't have W3W Search channel configured but it makes a lot of stack trace on server start because of missing API-key. The stack trace can be ignored but this PR adds a mechanism for components to signal that they were not initialized properly (throwing ComponentSkippedRuntimeException in init) and shouldn't be added to components register without printing out all that stack trace.