Check for warnings (#2850)

* check for warnings

* test run

* prebuild wasm binaries, pre-test is not needed for now

* will run everywhere but PRs

* lost warnings

* lost warnings

* try warnings with tests

* Update expected stderr in UI tests

* added to RUSTFLAGS

* another way of collecting warnings

* bump impl_version

* fix int tests parser

* revert demis changes and impl version bump

* no need to collect warnings in int test