Long identifiers support

[yahonda]

Steps to reproduce

Please refer https://github.com/rsim/oracle-enhanced/tree/master/guides/bug_report_templates
to create an executable test case

Expected behavior

If the database server version is 12.2 or higher the max identifier length is 128 byte.
else if it is 12.1 or lower version it is 30 byte.

We need to consider if user can stay 30-byte identifier even if the database version is 12.2 or higher.

Actual behavior

Identifier length is 30 byte whichever database server version is.

System configuration

Rails version:Next major

Oracle enhanced adapter version:Next major

Ruby version:n/a

Oracle Database version:12.2 or higher

[yahonda]

https://docs.oracle.com/database/122/NEWFT/new-features.htm#GUID-64283AD6-0939-47B0-856E-5E9255D7246B

[yahonda]

#1703 has been merged to master.