Note: cannot name a file XXX_wasm.go.  Go build will treat this file as
a wasm target.  Lots of mystic failures ...

With this, we allow user to run WebAssembly, which essentially allow
user to run a UDF written in any language.   This indeed make the
dev flow a little bit longer/harder, but it is significantly easier
than write plsql and debug plsql.

Wasm function only takes string args.  One common way is to encode
the args into a json string.  json_encode, concat_ws, group_concat
is your friend.

Return is a string as well.  jq and unnest can be used to decode
json.

…in#17448)

add concurrency when fetch objects of table

Approved by: @daviszhen, @XuPeng-SH, @reusee