E021-09: TRIM function (#114)
`TRIM` can be constructed in several forms:
TRIM(
[ [ { LEADING | TRAILING | BOTH } ] [ trim_character ] FROM ]
trim_source
)
If `LEADING`, `TRAILING` or `BOTH` is not provided, `BOTH` is used.
If `trim_character` is not provided, a space (`' '`) is used.
VALUES TRIM(' hello world ');
-- COL1: hello world
VALUES TRIM('a' FROM 'aaababccaa');
-- COL1: babcc
VALUES TRIM(LEADING 'a' FROM 'aaababccaa');
-- COL1: babccaa
VALUES TRIM(TRAILING 'a' FROM 'aaababccaa');
-- COL1: aaababcc
