scripted-diff: Use std::span over Span

-BEGIN VERIFY SCRIPT-

 ren() { sed -i "s!\<$1\>!$2!g" $( git grep -l "$1" -- "./src" ":(exclude)src/span.h" ":(exclude)src/leveldb/db/log_test.cc" ) ; }

 ren Span            std::span
 ren AsBytes         std::as_bytes
 ren AsWritableBytes std::as_writable_bytes

 sed -i 's!SpanPopBack(Span!SpanPopBack(std::span!g' ./src/span.h

-END VERIFY SCRIPT-

src/base58.h

@@ -22,7 +22,7 @@
 /**
  * Encode a byte span as a base58-encoded string
  */
-std::string EncodeBase58(Span<const unsigned char> input);
+std::string EncodeBase58(std::span<const unsigned char> input);
 
 /**
  * Decode a base58-encoded string (str) into a byte vector (vchRet).
@@ -33,7 +33,7 @@ std::string EncodeBase58(Span<const unsigned char> input);
 /**
  * Encode a byte span into a base58-encoded string, including checksum
  */
-std::string EncodeBase58Check(Span<const unsigned char> input);
+std::string EncodeBase58Check(std::span<const unsigned char> input);
 
 /**
  * Decode a base58-encoded string (str) that includes a checksum into a byte