Fix calls to removed V8 External API

[Nidrax]

As per https://chromium-review.googlesource.com/c/v8/v8/+/7562476
The External::New and External::Value now require explicit ExternalPointerTypeTag argument.
This change fixes outdated calls to now defunct API.

Closes #49

[Nidrax]

Can't be merged due to incompatible library versions between macOS, Msys2 and Ubuntu used for GitHub workflows and the dylibs signage breaking on macOS. Will be replaced by #51
In the future either the V8 lib versions will be aligned or will have to be fixed by working around the OS compilation flags.
In the long run we might want to develop our own scripting API with smaller footprint either based on Python or Lua, probably drop V8 completely and either use Duktape only or replace it with some alternative, slower but more lightweight JS engine library for optional backawrds LS scripts compatibility.