chore: update default dfx version to 0.16.0

[ericswanson-dfinity]

This update to dfx 0.16.0 doesn't introduce any new test failures. It does change how some of them fail, since dfx 0.16.0 supports gzipped wasm, so the tests get farther.

The path filtering logic in the test workflows doesn't always work (skips some tests that should run based on what files changed in the PR), so I will follow up this PR with subsequent PRs to update individual tests to 0.16.0.

The changes to the motoko-invoice canister tests are:

• give the workflows (e2e/unit) unique names so that they both show up in test results
• make it so the workflow notices this error, rather than failing after 45 minutes due to 15s per-test timeouts:

(node:4971) UnhandledPromiseRejectionWarning: Error: Mismatch between expected canister id and current invoice canister id