fix bash module

[sancppp]

fix #490

• The number of built-in commands without returned value (such as exit, exec) is limited, perhaps they can be treated specially.
• The uretprobe/readline function should check whether the key already exists, and if so, perform an append operation (in fact, this logic should be done in user space rather than in kernel space. The BPF program merely sends the collected data to user space.).

So in this PR:

• The BPF program in kernel space merely sends the collected data to user space.
• Change bashEvent.eventType from EventTypeOutput to EventTypeEventProcessor.
• Rebuild iworker.go.Implemented a new bashEventWorker struct for the iworker interface to handle bashevent.

[ruitianzhong]

Can we just reuse the String function for BashEvent to avoid the extensive modification for iworker ?

[cfc4n]

Rebuild iworker.go.Implemented a new bashEventWorker struct for the iworker interface to handle bashevent.

This approach is not very elegant. It should use the same worker to process HTTP requests, HTTP responses, and bash, regardless of which one it is processing. It only needs to implement a bash IParser.

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