* build(android): unify snapshot/ime helper build+package scripts
Replace the four ~75%-duplicated shell scripts with one parameterized
build script and one parameterized package script, mirroring
scripts/build-xcuitest-apple.sh's env-var-driven pattern. The helper
is selected via AGENT_DEVICE_ANDROID_HELPER or a first positional arg;
per-helper differences (HELPER_DIR/PACKAGE_NAME, snapshot's
test-compile+run step, ime's aapt2 resource-compile step, and the
manifest JSON fields) live in small case blocks.
All package.json entry points keep their names and output paths.
Verified byte-level equivalence between main and this branch: identical
unzip -l listings, identical classes.dex SHA-256 for both helpers, and
identical manifest fields (only the per-signing-run sha256 differs).
Fixes#1461
* chore: drop stale android/multitouch-helper .gitignore entries
The multitouch helper was consolidated away in #1281; these two lines
were never cleaned up.
Michał Pierzchała