Instead of inheriting from testing::Test's SetUp and TearDown we add
new methods 'testSetUp' and 'testTearDown'. This helps prevent a common
error of forgetting to call the base class method.

Also add a check in the ANGLETest destructor that SetUp and TearDown
have been called.

Bug: angleproject:3393
Change-Id: Iab211305cc06ffea9ca649e864ddc9b180f2cba0
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1593960Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>