Fix some error handling in the db2 adapter
Fix some error handling in the db2 adapter

Recognize that DB2CLI::SQL_NO_DATA_FOUND does not indicate an
error, and handle invalid handle and still executing errors
with disconnects.  Also, show the underlying error type or type
code in the exception message for easier debugging.

dennis-d/custom_sequel,gferguson-gd/sequel,reubano/sequel,beni55/sequel,nicohvi/sequel,knut2/sequel,seeARMS/sequel,yazshel/sequel,seeARMS/sequel,offshore-safety/sequel,nju520/sequel,t-morgan/sequel,mpalmer/sequel,pfarrell/sequel,nju520/sequel,nicohvi/sequel,knut2/sequel,uhoh-itsmaciek/sequel,bigfix/sequel,davidbegin/sequel,chef/sequel,offshore-safety/sequel,yazshel/sequel,mpalmer/sequel,reubano/sequel,freshpay/sequel,davidbegin/sequel,dennis-d/custom_sequel,beni55/sequel,uhoh-itsmaciek/sequel,gferguson-gd/sequel,offshore-safety/sequel,t-morgan/sequel,freshpay/sequel,Marketcircle/sequel,pfarrell/sequel