Automate libphx.lua

[HaronK]

There are several declarations in the engine/lib/phx/script/ffi/libphx.lua file that should be now manually added or updated when you change Rust code.

All this can be automated with proc macro generation.

Sections:

1. Basic Typedefs - for non standard types (mostly enums or typedefs) we can put these declarations in their own generated *.lua files.
2. Opaque Structs - those are impl blocks. Also can be automatically generated.
3. libphx.Opaques - list of names of the opaque structures. Can be autogenerated.
4. Transparent Structs - these ones mostly manual thing but theoretically can be also autogenerated (by adapting proc macro for structs).
5. libphx.Structs - list of names of the transparent structures. Same as previous one.

After this all Lua bindings generation will be automatic (probably except transparent structures, but they should be rarely changed), so developers should not do any additional fixes manually.