Fixed behavior:
- when comparing sign was determined as angle bracket
- when in complex combination brackets, an opposite bracket
was detected not correct
- not correct mismatch case highlightning
Added tests for the cases form bug 26395
Fixes: QTCREATORBUG-26400
Fixes: QTCREATORBUG-26395
Change-Id: Ic45566d2677f80fb9a8e4fe830307254dd1db51d
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>