Move r/t/SLTestWrapper to sl/SLWrapper

Wrapper is used in the SL Shim code. Moved the wrapper out of
test directory and made it part of support library loader lib.

Few bug fixes in the wrapper in struct assignment operators,
added retention of operand types, needed for easy setting
input/output operand values.

Bug: 172925288
Test: NeuralNetworksSupportLibraryTest
Change-Id: I41c69cf260504260a2863e2a3ec55a21af534f7f
Merged-In: I41c69cf260504260a2863e2a3ec55a21af534f7f
(cherry picked from commit 3a2147871ba3e1725b1ff559f57c6861751a3ffe)
8 files changed