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/util/feefrac.cpp

@@ -7,10 +7,10 @@
 #include <array>
 #include <vector>
 
-std::partial_ordering CompareChunks(Span<const FeeFrac> chunks0, Span<const FeeFrac> chunks1)
+std::partial_ordering CompareChunks(std::span<const FeeFrac> chunks0, std::span<const FeeFrac> chunks1)
 {
     /** Array to allow indexed access to input diagrams. */
-    const std::array<Span<const FeeFrac>, 2> chunk = {chunks0, chunks1};
+    const std::array<std::span<const FeeFrac>, 2> chunk = {chunks0, chunks1};
     /** How many elements we have processed in each input. */
     size_t next_index[2] = {0, 0};
     /** Accumulated fee/sizes in diagrams, up to next_index[i] - 1. */