Writing to readonly memory should call cpu_transaction_failed
Description of problem:
Currently if a guest writes to ROM memory on a system that doesn't have some other form of memory protection enabled, QEMU will silently ignore the write (https://gitlab.com/qemu-project/qemu/-/blob/master/accel/tcg/cputlb.c#L2432). Instead, it should call cpu_transaction_failed (similar to what happens when a MMIO operation fails in `io_writex` and other places). For CPUs that don't care, it'll continue to be ignored, but for other CPUs the user will get a warning (with `-d guest_errors`) or an exception as appropriate.
Steps to reproduce:
N/A
Additional information:
The documentation for do_transaction_failed says:

```
@do_transaction_failed: Callback for handling failed memory transactions
(ie bus faults or external aborts; not MMU faults)
```

which seems reasonably well suited for this case. Here's an overview of what different CPUs currently do if do_transaction_failed is called:

alpha_cpu_do_transaction_failed:

* raises a EXCP_MCHK

arm_cpu_do_transaction_failed:

* raises ARMFault_SyncExternal with EXCP_DATA_ABORT

loongarch_cpu_do_transaction_failed:

* raises EXCCODE_ADEM

m68k_cpu_transaction_failed:

* raises EXCP_ACCESS (M68040 only)

mb_cpu_transaction_failed:

* raises EXCP_HW_EXCP with ESR_EC_DATA_BUS

mips_cpu_do_transaction_failed:

* raises EXCP_DBE (data bus error)

riscv_cpu_do_transaction_failed:

* raises RISCV_EXCP_STORE_AMO_ACCESS_FAULT

sparc_cpu_do_transaction_failed:

* raises an MMU fault

xtensa_cpu_do_transaction_failed

* raises LOAD_STORE_PIF_ADDR_ERROR_CAUSE