[mlir][bytecode] Check that bytecode source buffer is sufficiently aligned. (#66380)

Before this change, the `ByteCode` test failed on CentOS 7 with
devtoolset-9, because strings happen to be only 8 byte aligned. In
general though, strings have no alignment guarantee.

Increase resource alignment in test to 32 bytes. 
Adjust test to sufficiently align buffer.
Add test to check error when buffer is insufficiently aligned.