Fix rare CiviReport error relating to long report names

Change civicrm_report_instance, report_id from 64 characters to 512 characters to match civicrm_option_value, value to avoid errors caused by truncating CiviCRM report name which are greater than 64 chars.

As a result, when a new report is created based on a custom report template which has a name greater than 64 characters. The stored report_id is truncated when the new report instance is created. The truncated report_id does not match the corresponding template from which it was created, which causes CiviCRM to throw errors like:

1. You have tried to access a report that does not exist.
2. Could not find template for the instance.'

For example, if I have a custom CiviCRM report with a report_url of au.com.agileware.constituentsummarymembershiptypereport/constituentsummarymembershiptype

CiviCRM will store only the first 64 characters of new report instances as the report_id: au.com.agileware.constituentsummarymembershiptypereport/constitu

And since this error does not actually indicate what the true nature of the problem is, this can waste a lot of time trying to solve and is very frustrating.

There should possibly be a warning in CiviCRM somewhere as well which reports or otherwise informs developers that CiviCRM cannot use reports which have names greater than X characters.

So for this issue, I recommend just increasing the size of the report_id field so that it matches the civicrm_option_value, value field, which is varchar 512.

Agileware Reference CIVICRM-283