[AMDAIECoreToStandard] Improve error message when core not isolated

[newling]

In case we hit this error again, I'd like the message to be more informative. The new error is something like:

<unknown>:0: error: 'arith.constant' op is not in the core in which it is used. Cores must be `isolated` before this point.
<unknown>:0: note: see current operation: %0 = "arith.constant"() <{value = 0 : i32}> : () -> i32
<unknown>:0: error: 'aie.device' op Failed to lower to LLVM
<unknown>:0: note: see current operation:
"aie.device"() <{device = 8 : i32}> ({

compared to old error, something like:

LLVM ERROR: operation destroyed but still has uses
Please report issues to https://github.com/iree-org/iree/issues and include the crash backtrace.
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
0  libIREECompiler.so 0x00007fa09d494f87 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 39
1  libIREECompiler.so 0x00007fa09d4931c0 llvm::sys::RunSignalHandlers() + 80

[jtuyls]

LGTM

[jtuyls]

You could put it in a utility function inside the CoreOp itself so it can be reused in different places. But I wouldn't spend effort on that for AIE ops and wait for it until we solely rely on AMDAIE ops.