Rewrite table building code with Lua

[lvjr]

Maybe we can rewrite table building code with Lua language in the future. This would make tabularray run much faster on LuaTeX.

[lvjr]

Since lua doesn't have catcodes, there might be some limitations in building tables with lua.

[user202729]

Just come across this -- maybe you already know but Lua has some support for tokens.

Lots of things need to be manually implemented though e.g. you can't create a control sequence not in the hash table on Lua side (but then Lua doesn't even have a built-in to concatenate to tables so maybe this is expected...)

https://tex.stackexchange.com/questions/45293/can-the-lua-part-of-luatex-know-about-tokens/