zink: fix up bo sizing for good and verify that it's definitely fixed

over time there have been a number of issues (#4738 (closed), !17217 (merged)) related to sizing of bo variables, specifically on drivers which do bounds checking of access vs the variable being accessed

the core issue is that zink doesn't do this bounds checking, so it's always a surprise when things are broken. to that end, this implements a bounds checker / optimizer for bo access that will delete oob loads/stores, which will immediately break any cases where the variables are incorrectly sized