Allow to specify multiple relay chain RPC urls for collator node (#1880)

* Allow specification of multiple urls for relay chain rpc nodes

* Add pooled RPC client basics

* Add list of clients to pooled client

* Improve

* Forward requests to dispatcher

* Switch clients on error

* Implement rotation logic

* Improve subscription handling

* Error handling cleanup

* Remove retry from rpc-client

* Improve naming

* Improve documentation

* Improve `ClientManager` abstraction

* Adjust zombienet test

* Add more comments

* fmt

* Apply reviewers comments

* Extract reconnection to extra method

* Add comment to reconnection method

* Clean up some dependencies

* Fix build

* fmt

* Provide alias for cli argument

* Apply review comments

* Rename P* to Relay*

* Improve zombienet test

* fmt

* Fix zombienet sleep

* Simplify zombienet test

* Reduce log clutter and fix starting position

* Do not distribute duplicated imported and finalized blocks

* fmt

* Apply code review suggestions

* Move building of relay chain interface to `cumulus-client-service`

* Refactoring to not push back into channel

* FMT

client/cli/src/lib.rs

@@ -293,9 +293,11 @@ pub struct RunCmd {
 	/// EXPERIMENTAL: Specify an URL to a relay chain full node to communicate with.
 	#[arg(
 		long,
-		value_parser = validate_relay_chain_url
+		value_parser = validate_relay_chain_url,
+		num_args = 0..,
+		alias = "relay-chain-rpc-url"
 	)]
-	pub relay_chain_rpc_url: Option<Url>,
+	pub relay_chain_rpc_urls: Vec<Url>,
 }
 
 impl RunCmd {
@@ -310,7 +312,7 @@ impl RunCmd {
 
 	/// Create [`CollatorOptions`] representing options only relevant to parachain collator nodes
 	pub fn collator_options(&self) -> CollatorOptions {
-		CollatorOptions { relay_chain_rpc_url: self.relay_chain_rpc_url.clone() }
+		CollatorOptions { relay_chain_rpc_urls: self.relay_chain_rpc_urls.clone() }
 	}
 }
 
@@ -318,7 +320,7 @@ impl RunCmd {
 #[derive(Clone, Debug)]
 pub struct CollatorOptions {
 	/// Location of relay chain full node
-	pub relay_chain_rpc_url: Option<Url>,
+	pub relay_chain_rpc_urls: Vec<Url>,
 }
 
 /// A non-redundant version of the `RunCmd` that sets the `validator` field when the