[Analyzer][StreamChecker] Changed representation of stream error state - NFC.

Summary:
State of error flags for a stream is handled by having separate flags
that allow combination of multiple error states to be described with one
error state object.
After a failed function the error state is set in the stream state
and must not be determined later based on the last failed function
like before this change. The error state can not always be determined
from the last failed function and it was not the best design.

Reviewers: Szelethus

Reviewed By: Szelethus

Subscribers: xazax.hun, baloghadamsoftware, szepet, a.sidorin, mikhail.ramalho, Szelethus, donat.nagy, dkrupp, gamesh411, Charusso, martong, ASDenysPetrov, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D80009