Enhance type inference for intercept and assertThrows

[vincentdehaan]

This PR makes it possible to leave out the type parameter on assertThrows and intercept. In this case, it will catch any Exception.

[cheeseng]

@vincentdehaan I tried to build and test this, but unfortunately I got quite a number of failing tests:

*** 78 TESTS FAILED ***
...
[error] Failed tests:
[error] 	org.scalatest.SuiteSuite
[error] 	org.scalatest.StatusSpec
[error] 	org.scalatest.RefSpecSpec
[error] 	org.scalatest.tools.XmlSocketReporterSpec
[error] 	org.scalatest.path.FunSpecSpec
[error] 	org.scalatest.path.FreeSpecSpec
[error] 	org.scalatest.ClueSpec
[error] 	org.scalatest.BeforeAndAfterEachAsyncSuite
[error] 	org.scalatest.AppendedCluesSpec
[error] 	org.scalatest.tools.DiscoverySuiteSuite
[error] 	org.scalatest.BeforeAndAfterAsyncSuite
[error] 	org.scalatest.AssertionsSpec
[error] 	org.scalatest.concurrent.JavaFuturesSpec
[error] 	org.scalatest.tools.FrameworkSuite
[error] 	org.scalatest.exceptions.PayloadSpec
[error] 	org.scalatest.OutcomeSpec
[error] 	org.scalatest.concurrent.EventuallySpec
[error] 	org.scalatest.concurrent.WaitersSpec
[error] 	org.scalatest.concurrent.ScalaFuturesSpec
[error] (scalatestFeatureSpecTest / Test / test) sbt.TestsFailedException: Tests unsuccessful
[error] (scalatestFunSuiteTest / Test / test) sbt.TestsFailedException: Tests unsuccessful
[error] (scalatestFlatSpecTest / Test / test) sbt.TestsFailedException: Tests unsuccessful
[error] (scalatestFreeSpecTest / Test / test) sbt.TestsFailedException: Tests unsuccessful
[error] (scalatestPropSpecTest / Test / test) sbt.TestsFailedException: Tests unsuccessful
[error] (scalatestFunSpecTest / Test / test) sbt.TestsFailedException: Tests unsuccessful
[error] (scalatestWordSpecTest / Test / test) sbt.TestsFailedException: Tests unsuccessful
[error] (scalatest-test / Test / test) sbt.TestsFailedException: Tests unsuccessful
[error] (scalactic-test / Test / test) sbt.TestsFailedException: Tests unsuccessful
[error] Total time: 248 s (04:08), completed Jun 22, 2021 11:09:51 AM

You may reproduce that by running

> sbt clean test