ref: Remove circular dependency in @sentry/node

[tkalliom]

When rolluping code that uses sentry, I got a warning for circular references in @sentry/node. Here’s a summary of what references what:

File                                       Member                                       Exported from package as
------------------------------------------+--------------------------------------------+--------------------------------
src/sdk.ts                                 export const defaultIntegrations             defaultIntegrations
`src/integrations/index.ts                 export OnUncaughtException                   Integrations.OnUncaughtException
 `src/integrations/onuncaughtexception.ts  export class OnUncaughtException             Integrations.OnUncaughtException
  `src/handlers.ts                         export function logAndExitProcess (@hidden)  (Handlers.logAndExitProcess)
   
   src/handlers.ts                         export function requestHandler               Handlers.requestHandler
   `src/sdk.ts                             export async function flush                  flush

This could be resolved by extracting either flush or logAndExitProcess to a lower-level module. I opted to move logAndExitProcess because it is not public and because it seems neat that a function that is only called from integrations is placed inside that directory, not above it.

[kamilogorek]

Thanks!