https://jira.percona.com/browse/PSTRESS-78

pstress-119 Option to manipulate length of CHAR, VARCHAR, BLOB
https://jira.percona.com/browse/PSTRESS-119

Introduced below new options

--columns-in-generated: maximum number of columns in a generated column
 default#: 6

--generated-stored: Probability of generated columns STORED or VIRTUAL
50 ==> equal chances of stored and virtual
100 => all columns are stored
0 => all columns are virtual
any other value sets the probability of stored column accordingly
default#: 50

--char-length: char column maximum length
 default#: 20

--varchar-length: varchar column maximum length.
 default#: 40

--blob-length: Maximum lenght of blob/text columns
TINYBLOB/TINYTEXT 1/4 of blob-length
TEXT/BLOB 1/3 of blob-length
MEDIUMBLOB/MEDIUMTEXT 1/2 of blob-length
LONGBLOB/LONGTEXT blob-length
 default#: 1000