SQL: support LOAD DATA INFILE Statement

[dl239]

desc: batch import data into OpenMLDB
format: import table file_path
ex: import demo_table1 file:///OpenMLDB/cli/examples/taxi_tour_parquet_all/raw_data.csv;

Desc: support LOAD DATA INFILE 'file_name' SQL Statement like MySQL
E.g: LOAD DATA INFILE 'hello.csv' INTO TABLE t1;

[aceforeverd]

different with import statements e.g mysql's https://dev.mysql.com/doc/refman/8.0/en/import-table.html

[aceforeverd]

As discussed in #494 , this import feature should better write as LOAD DATA INFILE, since it do not import schema but just data. Also documented by MySQL:

LOAD DATA is the complement of SELECT ... INTO OUTFILE.

which is more suitable with #455

[vagetablechicken]

load data supports OPTIONS, ref #455 (comment)
Currently, we can support none, but should warn it.