Remove unused includes from blockfilter.h

This removes unused includes, primitives/block found manually, and the
others by iwyu:

blockfilter.h should remove these lines:
- #include <serialize.h>  // lines 16-16
- #include <undo.h>  // lines 18-18

src/index/blockfilterindex.cpp

@@ -10,6 +10,7 @@
 #include <index/blockfilterindex.h>
 #include <logging.h>
 #include <node/blockstorage.h>
+#include <undo.h>
 #include <util/fs_helpers.h>
 #include <validation.h>
 

src/index/blockfilterindex.h

@@ -12,6 +12,8 @@
 #include <index/base.h>
 #include <util/hasher.h>
 
+#include <unordered_map>
+
 static const char* const DEFAULT_BLOCKFILTERINDEX = "0";
 
 /** Interval between compact filter checkpoints. See BIP 157. */