lua: define operator precedence in Lua.

[soasme]

[soasme]

I'm not going to merge this PR anytime soon since this approach will increase the parse time significantly. It took nearly 20s even if the cli is compiled with -O2 option.

54/54 Test #53: lua-5.4.3/*.lua ..............................   Passed   19.89 sec

A better approach may be introducing precedence climbing at Peppa PEG specification level.