Restructure 580-fp16 tests into functions

There are a lot of tests present in main and their number is increasing.
Restructure these into functions to make it easier to find related tests.

Test: 580-fp16
Test: art/test/testrunner/run_build_test_target.py -j80 art-test-javac
Change-Id: I8d0e766d1ebab0cf6d6829300a1d09c4a2244365
1 file changed