slot_actions: Add Equivocating Blob Sidecars Action

[marioevz]

Adds a slot action that performs the following steps:

• Creates an equivocating header by modifying the graffiti
• Creates two bundles of sidecars: one from the original/valid block, and another one for the equivocating header
• Broadcasts the sidecar bundles to two different sets of peers
• Broadcasts the correct block to all peers

Expectation is that clients are able to recover from this.

Slot action can be enabled using the json:

{
	"name": "equivocating_blob_sidecars",
	"broadcast_blobs_first": true
}