seek: defer matcher check until more info is known

Sped up seeking for files to operate on, when using options like --copies
or --in, by around 20%.

Benchmark showed an increase for --copies from 155 seconds to 121
seconds, and --in remote will be similar to that.

For --in here, the speedup was less, 5-10% or so.

(both warm cache)

This commit was sponsored by Jack Hill on Patreon.

Types/FileMatcher.hs

@@ -62,6 +62,10 @@ data MatchFiles a = MatchFiles
 	, matchNeedsFileContent :: Bool
 	-- ^ does the matchAction need the file content to be present in
 	-- order to succeed?
+	, matchNeedsKey :: Bool
+	-- ^ does the matchAction look at information about the key?
+	, matchNeedsLocationLog :: Bool
+	-- ^ does the matchAction look at the location log?
 	}
 
 type FileMatcher a = Matcher (MatchFiles a)