Move tests failing the frontend to FrontEndTests

...resources/regression/frontends/error/simple/Asserts.scala

...ces/regression/frontends/error/simple/ConvertBigInt.scala

...urces/regression/frontends/error/simple/InstanceOf1.scala

...ces/regression/frontends/error/simple/LiteralBigInt.scala

...sources/regression/frontends/error/simple/NotEquals.scala

...t/resources/regression/frontends/error/xlang/Array1.scala

.../resources/regression/frontends/error/xlang/Array10.scala

...t/resources/regression/frontends/error/xlang/Array2.scala

...t/resources/regression/frontends/error/xlang/Array3.scala

...t/resources/regression/frontends/error/xlang/Array4.scala

...t/resources/regression/frontends/error/xlang/Array5.scala

...t/resources/regression/frontends/error/xlang/Array6.scala

...t/resources/regression/frontends/error/xlang/Array7.scala

...t/resources/regression/frontends/error/xlang/Array8.scala

...t/resources/regression/frontends/error/xlang/Array9.scala

src/test/resources/regression/frontends/passing/Fields.scala

...st/resources/regression/frontends/passing/Operators.scala

src/test/scala/leon/test/frontends/FrontEndsTest.scala

...n/test/verification/PureScalaVerificationRegression.scala

...scala/leon/test/verification/VerificationRegression.scala