[FEATURE] Unit tests for IOC

[RichardBrown384]

Is your feature request related to a problem? Please describe. The IOC currently isn't sufficiently tested.

Describe the solution you'd like

• [X] Tests reading and writing to the internal registers
• [X] Tests reading and writing to the various banks relevant to the A3000 (FDC, Latch A+B)
• [X] Tests checking that the appropriate IRQ/FIQ bits are set in response to various system events
• [ ] Tests validating that the IOCTimers work (checking that T0 and T1 set appropriate bits on expiry, the timers count down at the correct rate)
• [ ] Tests that validate the keyboard actions and data transfer rates

Describe alternatives you've considered None

Additional context None