fix: lib/runtime: update sign_ funcs to return fixed size byte optional

[noot]

Changes

• update sign_ functs to return fixed size byte optional
• update life not to error if core_version doesn't exist (needed for host API tester)

Tests

go test ./lib/runtime/wasmer/ -run Test_ext_crypto_ed25519_sign_version_1
go test ./lib/runtime/wasmer/ -run Test_ext_crypto_sr25519_sign_version_1
go test ./lib/runtime/life

Checklist

• I have read CODE_OF_CONDUCT and CONTRIBUTING
• I have provided as much information as possible and necessary
• I have reviewed my own pull request before requesting a review
• All integration tests and required coverage checks are passing

Issues

related to #1105

[FlorianFranzen]

This does indeed fix the encoding issue and the returned signature now pass verification.

I would however like to ask you to increase the error level on verification failures in ed25519:

--- a/lib/runtime/wasmer/imports.go
+++ b/lib/runtime/wasmer/imports.go
@@ -636,7 +636,7 @@ func ext_crypto_sr25519_verify_version_1(context unsafe.Pointer, sig C.int32_t,
   }

   if ok, err := pub.VerifyDeprecated(message, signature); err != nil || !ok {
-    logger.Debug("[ext_crypto_sr25519_verify_version_1] failed to verify sr25519 signature")
+    logger.Error("[ext_crypto_sr25519_verify_version_1] failed to verify sr25519 signature")
     // TODO: fix this, fails at block 3876
     return 1
   }

The life issue however still exists, as the call to a none-existing Version() still causes a panic. Maybe calling Version() similar to how it is done on the wasmer backend (e.g. when the version field is needed but nil and not on initialization) would be the easiest solution.