* test: Add gatsby-browser, gatsby-node and integration tests

* ref: Make `@sentry/tracing` required dependency

* fix: Remove require.ensure call to prevent delay in Sentry init

* Add integration for offline support

Offline events are cached in the browser with localforage.

* Add logging statements

* Move 'offline' to the integrations package

* Revert to import assignment

I thought this build was passing, but it looks like there is not an easy way to use a standard import for localforage in this library.

* Use Hub.captureEvent instead of adding @sentry/minimal

* Use localforage types

* Remove async/await syntax to keep bundle size down

* Check for addEventListener in global

* Add tests for Offline integration

* Fixing lockfile after migrating to @sentry/integrations

* Add TS compiler flag to allow import of localforage

* Handle scenario where app has stored events from previous offline session

* Add config for maxStoredEvents with a default limit of 30

* Address new linter rules

ref https://github.com/getsentry/sentry-javascript/blob/master/packages/browser/.npmignore

https://unpkg.com/browse/@sentry/browser/build/ is Found
https://unpkg.com/browse/@sentry/tracing/build/ is NotFound

* build: Lock in TypeScript to 3.7.5

* build: Prevent anyone from ever changing typescript version

* fix: Force SinonStub to work

Closes #2830
Throwing a string in node causes the exception to appear as 'Sentry syntheticException'
in Sentry UI. This saves the string as a message of the syntheticException
so that the correct message is reported.

Co-authored-by: Katie Byers <[email protected]>