feat(exex, node): check ExEx head against the node head

[shekhirin]

Ref #10489

[mattsse]

I think they're two ways to go about this
a) like this pr does, return context on launch

or a different install process that not only receives the ExEx context but also a way to communicate this to the manager, imo this would be the more elegant approach.
for example, during install, you create a subscription by providing the ExExHead as an argument, so that

reth/crates/exex/exex/src/context.rs

Lines 19 to 33 in 516ae50

	/// Channel used to send [`ExExEvent`]s to the rest of the node.
	///
	/// # Important
	///
	/// The exex should emit a `FinishedHeight` whenever a processed block is safe to prune.
	/// Additionally, the exex can pre-emptively emit a `FinishedHeight` event to specify what
	/// blocks to receive notifications for.
	pub events: UnboundedSender<ExExEvent>,
	/// Channel to receive [`ExExNotification`]s.
	///
	/// # Important
	///
	/// Once a an [`ExExNotification`] is sent over the channel, it is considered delivered by the
	/// node.
	pub notifications: Receiver<ExExNotification>,

is no longer created beforehand but the subscriptions will be created specific to the ExExHead

[mattsse]

why does this take just the block hash?

[mattsse]

this needs proper docs,

do we think we will eventually require additional info from the exex?
if so we could perhaps change this to

struct ExExInfo {
   head: Option<ExExHead>
}

[shekhirin]

Going with the second approach in another PR