Introduce a SQL syntax for creating inverted index and related metadata changes.
```
-- create table with INVERTED index
CREATE TABLE httplogs (
ts datetime,
clientip varchar(20),
request string,
status smallint,
size int,
INDEX idx_size (size) USING INVERTED,
INDEX idx_status (status) USING INVERTED,
INDEX idx_clientip (clientip) USING INVERTED PROPERTIES("parser"="none")
)
DUPLICATE KEY(ts)
DISTRIBUTED BY RANDOM BUCKETS 10
-- add an INVERTED index to a table
CREATE INDEX idx_request ON httplogs(request) USING INVERTED PROPERTIES("parser"="english");
```
