can't use the META function on CREATE INDEX

a number of customers bury the type of docs into their doc key. indexing based on type generally helps many queries thus the following type of index become super useful to help improve query perf. However we don't seem to have the ability to use META function in indexing;
CREATE INDEX i3 on `beer-sample`(META(`beer-sample`).id) USING GSI;

we need to add support for META function to enable this in CREATE INDEX.

Below will be supported:

Meta().id