Implement fraudproof generation mode in cosmos-sdk

[Manav-Aggarwal]

Before: When an optimint full node finds a fraudulent block, it tells cosmos-sdk to go into fraudproof generation mode.

After: optimint can supply cosmos-sdk with a fraudulent block and tell it to actually generate a fraudproof.

In the fraudproof generation mode, a cosmos-sdk app reverts its state to a previous state before the fraudulent block was applied and enables tracing for modules specified by optimint, so it is prepared to receive a fraudulent block again but this time log all the operations that happen inside the block.

Parts covered from the cycle of a fraudproof:

Optimint Full Node (Producer of fraudproof)
2. In the fraudproof generation mode, a cosmos-sdk app reverts its state to a previous state before the fraudulent block is applied and enables tracing.

Parent issue: #245

[Manav-Aggarwal]

Fraudproof generation mode is not needed anymore since we use IAVL trees now. Closed by: rollkit#1