feat(api/build/v8): Use blob to build v8

[xdoardo]

wee8-custom-builds is a repo akin to llvm-custom-builds that builds v8 in wee8 mode producing an archive containing the necessary static libraries to build wasmer with the v8 feature enabled.

This patch

1. removes the v8-cmake submodule
2. downloads the archive and uses its contents during linking
3. introduces a copy of the wasm.h header from the v8 repo