Locks and Multi fan-in and fan-out

[Suhas-G]

Issues:
Locks: When multiple writers are writing to same wire, its necessary to lock the shared memory while write is in progress.
Enable in FSM: In the case of FSMs, a block should be able to disable itself after it transitions to the next state. But the Enable wire of a block is an input block and not writeable by it. This PR changes this by giving a separate interface for enable wire as a property of the inputs block. And also allows the block to disable by setting inputs.enable = False to disable itself safely.
Multi Fan-in and Fan-out: When we have the scenario of multiple wires going to same input or same output having multiple wires to different inputs, we have to use the same underlying shared memory so that data can be modified correctly.

[toshan-luktuke]

Tested with:

• Multiple inputs (2 - 3 wires coming in a single block)
• Multiple outputs (2 - 3 wires going out of a single block)

Remaining:

• FSM Testing with Enable

[toshan-luktuke]

I'm not able to figure out how the enable implementation is intended to work, I got it working but I had to make a few changes to the code here and there.
If possible can you give an example of the intended way to use it?

[Suhas-G]

Did the fsm structure with enable I showed work? Shall I merge this PR?

[toshan-luktuke]

Let's merge outputs.py and main.py. I've made some modifications to inputs.py to write to the Shared Memory like we discussed. Its better if I make a separate PR for that