In previous implementation `processResponse` returned `true` if
`resolveAPIFailures` is set and status failure is received. This led to
post-processing of the results, which no longer pays attention to the
status. For example, `ObjectHead` returned `unexpected header type`
error due to empty body.
Make `contextCall.processResponse` to return success flag regardless of
`resolveAPIFailures` setting. Make `contextCall.processCall` to return
`err` field presence flag on `processResponse` false return.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
85e3c7b087