Renderscript: rename .rs extension to .rscript

Reserve .rs extension for Rust.

Update test results to expect the new extension.

Bug: 137365032
Test: make checkbuild
Test: cd frameworks/compile/slang/tests
    ./slang_tests.py
Test: atest CtsRenderscriptTestCases
Test: CtsRsCppTestCases

Exempt-From-Owner-Approval: Clean CP
Change-Id: I53417fc10c589a845e1cefe8d41f71f8a8de1097
Merged-In: I53417fc10c589a845e1cefe8d41f71f8a8de1097
(cherry picked from commit 8bdd9e24da88bc85a80cb1794589bceb1c1e42ce)
(cherry picked from commit 60579e139639c1b7e3f64416936fa709f8dd102a)
424 files changed