Failable blocks / Improve error handling

[MaxVerevkin]

The use of refresh_interval_failure in #1366 made me wonder if it can be applied to other blocks in a generic way.

Here is a rough idea: when an error in a block occurs, the block's state will be set to error_state and the text will be set according to error_format. Then the block will be restarted after error_interval. Clicking on the block will show the full error message. Clicking again will hide the full error message.

There is a major issue though: some blocks spawn threads. The situation is better for async implementation, as those threads are at least abortable (edit: spawn_blocking() is not really abortable).

[MaxVerevkin]

Actually, it might be easier than I thought. There's no need to fully restart the blocks. Instead, each block can be composed of failable but recoverable parts.

As an example, here's a part of github's block from my prototype:

let total = api.recoverable(|| get_total(&request), "Oh no!").await?;

That's it. Nothing else needed on the block's side. That's how it looks:

rec.mp4

[ammgws]

Closing this as it's implemented in master now.