load Goerli metadata from goerli repo

The `eth2-networks` repo often receives metadata updates with a delay.
Switch to `goerli` repo to obtain the latest config (Dencun scheduling)
when it is updated. This is in line with how Sepolia / Holesky work.

- eth-clients/goerli#178

.gitmodules

@@ -220,6 +220,11 @@
 	url = https://github.com/arnetheduck/nim-results.git
 	ignore = untracked
 	branch = master
+[submodule "vendor/goerli"]
+	path = vendor/goerli
+	url = https://github.com/eth-clients/goerli
+	ignore = untracked
+	branch = main
 [submodule "vendor/holesky"]
 	path = vendor/holesky
 	url = https://github.com/eth-clients/holesky

beacon_chain/networking/network_metadata.nim

@@ -302,7 +302,7 @@ elif const_preset == "mainnet":
         vendorDir & "/eth2-networks/shared/mainnet/genesis.ssz")
 
       praterGenesis* = slurp(
-        vendorDir & "/eth2-networks/shared/prater/genesis.ssz")
+        vendorDir & "/goerli/prater/genesis.ssz")
 
       sepoliaGenesis* = slurp(
         vendorDir & "/sepolia/bepolia/genesis.ssz")
@@ -314,7 +314,7 @@ elif const_preset == "mainnet":
       useBakedInGenesis = some "mainnet")
 
     praterMetadata = loadCompileTimeNetworkMetadata(
-      vendorDir & "/eth2-networks/shared/prater",
+      vendorDir & "/goerli/prater",
       some goerli,
       useBakedInGenesis = some "prater")
 

beacon_chain/networking/network_metadata_mainnet.S

@@ -36,7 +36,7 @@ cdecl(eth2_mainnet_genesis_size):
     .quad    eth2_mainnet_genesis_end - eth2_mainnet_genesis_data
 
 eth2_goerli_genesis_data:
-    .incbin "eth2-networks/shared/prater/genesis.ssz"
+    .incbin "goerli/prater/genesis.ssz"
 eth2_goerli_genesis_end:
     .global cdecl(eth2_goerli_genesis_size)
     .p2align 3