Reenable integration tests

[kateinoigakukun]

Export main and execute _initialize and main in test entry

IntegrationTests are unintentionally disabled since 0a38d705e0c310f236599e2a0d62afa8012578db because reactor mode doesn't export _start and WASI.start doesn't do anything except setting the instance to WASI module. So export main manually, and call _initialize according to the "new-style commands" described in https://github.com/WebAssembly/WASI/blob/59cbe140561db52fc505555e859de884e0ee7f00/legacy/application-abi.md#current-unstable-abi

Symbol support (081784b34ad94c91eddccca58f1592ce181328ad) broke tests silently, so revert it for now.

[kateinoigakukun]

CC: @j-f1

[github-actions[bot]]

Time Change: +9,543ms (95%) 🆘

Total Time: 9,962ms

Test name	Duration	Change
Serialization/Swift Int to JavaScript	3,036.25ms	+3,036.25ms (100%)	🆘
Serialization/Swift String to JavaScript	3,110.25ms	+3,110.25ms (100%)	🆘
Object heap/Increment and decrement RC	3,390.5ms	+3,390.5ms (100%)	🆘

ℹ️ View Unchanged

| Test name | Duration | Change | | :--- | :---: | :---: | | Serialization/Write JavaScript number directly | 212.5ms | +6.25ms (2%) | | Serialization/Write JavaScript string directly | 212.5ms | -0.25ms |

_{performance-action}