Add length-check for reading char/varchar from tables w/ a external location

spark-sql> INSERT INTO t2 VALUES ('1', 'b12345');
Time taken: 0.141 seconds
spark-sql> alter table t set location '/tmp/hive_one/t2';
Time taken: 0.095 seconds
spark-sql> select * from t;
1 b1234
1 a
1 b

the above case should fail rather than implicitly applying truncation