Add support for exactOptionalPropertyTypes flag from TypeScript 4.4

[kamilogorek]

ref: #3960

[immerrr]

@kamilogorek @HazAT

Looks like the support for the "exactOptionalPropertyTypes" is still not implemented, even though this issue is closed. Would you be able to tell if it is on the roadmap still?

Enabling the option is recommended in TS doc and according to #18024, it is now enabled by default when running tsc --init, so the number of people who will come asking will increase in the future. You can kind of work it around with things like

Sentry.init({
  ...( dsn !== undefined ? { dsn } : undefined ),
})

but it's not at all pretty.