feat: add ed25519 signature verify program

Solang requires a method for verify ed25519 signatures. Add a new
builtin program at address Ed25519SigVerify111111111111111111111111111
which takes any number of ed25519 signature, public key, and message.
If any of the signatures fails to verify, an error is returned.

The changes for the web3.js package will go into another commit, since
the tests test against a released solana node. Adding web3.js ed25519
testing will break CI.

docs/src/developing/runtime-facilities/programs.md

@@ -65,6 +65,48 @@ to the BPF Upgradeable Loader to process the instruction.
 
 [More information about deployment](cli/deploy-a-program.md)
 
+## Ed25519 Program
+
+Verify ed25519 signature program. This program takes an ed25519 signature, public key, and message.
+Multiple signatures can be verified. If any of the signatures fail to verify, an error is returned.
+
+- Program id: `Ed25519SigVerify111111111111111111111111111`
+- Instructions: [new_ed25519_instruction](https://github.com/solana-labs/solana/blob/master/sdk/src/ed25519_instruction.rs#L31)
+
+The ed25519 program processes an instruction. The first `u8` is a count of the number of
+signatures to check, which is followed by a single byte padding. After that, the
+following struct is serialized, one for each signature to check.
+
+```
+struct Ed25519SignatureOffsets {
+    signature_offset: u16,             // offset to ed25519 signature of 64 bytes
+    signature_instruction_index: u16,  // instruction index to find signature
+    public_key_offset: u16,            // offset to public key of 32 bytes
+    public_key_instruction_index: u16, // instruction index to find public key
+    message_data_offset: u16,          // offset to start of message data
+    message_data_size: u16,            // size of message data
+    message_instruction_index: u16,    // index of instruction data to get message data
+}
+```
+
+Pseudo code of the operation:
+
+```
+process_instruction() {
+    for i in 0..count {
+        // i'th index values referenced:
+        instructions = &transaction.message().instructions
+        signature = instructions[ed25519_signature_instruction_index].data[ed25519_signature_offset..ed25519_signature_offset + 64]
+        pubkey = instructions[ed25519_pubkey_instruction_index].data[ed25519_pubkey_offset..ed25519_pubkey_offset + 32]
+        message = instructions[ed25519_message_instruction_index].data[ed25519_message_data_offset..ed25519_message_data_offset + ed25519_message_data_size]
+        if pubkey.verify(signature, message) != Success {
+            return Error
+        }
+    }
+    return Success
+}
+```
+
 ## Secp256k1 Program
 
 Verify secp256k1 public key recovery operations (ecrecover).