Include env/RT in generated definitions

[dcodeIO]

With the definitions now being in a format that can be picked up by bundlers (anticipating ESM integration) even when not using the loader, it may be useful to also declare the memory and the table, as well as exported runtime helpers.

• memory if exported
• table if exported
• _start if explicit
• __new, __pin, __unpin, __collect and __rtti_base if exported
• __setArgumentsLength if there are exported varargs functions

Also fixes #1900

• I've read the contributing guidelines

[dcodeIO]

Test failure is v8-canary missing builds.