Add `mithril-client-wasm` tests in multi platform test #5221

All 784 tests pass in 8m 52s

3 files ±0 33 suites ±0 8m 52s ⏱️ +9s
784 tests ±0 784 ✅ ±0 0 💤 ±0 0 ❌ ±0
857 runs ±0 857 ✅ ±0 0 💤 ±0 0 ❌ ±0

Results for commit c5c14d2. ± Comparison against earlier commit 6b54328.