NDK events and minidumps should be sent within the same envelope

[marandaneto]

Source #1256 (comment)

[marandaneto]

this is a blocker for breakpad support

[marandaneto]

theres an issue that if sending event and attachment in different envelopes, it may cause an error rendering the event since the attachment isn't ingested yet, solving this issue, also solves this one for free

[kahest]

closing as outdated and low prio/impact