info: Allow using matching options in more situations

File matching options like --include will be rejected in situations where
there is no filename to match against. (Or where there is a filename but
it's not relative to the cwd, or otherwise seemed too bothersome to match
against.)

The addition of listKeys' was necessary to avoid using more memory in the
common case of "git-annex info". Adding a filterM would have caused the
list to buffer in memory and not stream. This is an ugly hack, but listKeys
had previously run Annex operations inside unafeInterleaveIO (for direct
mode). And matching against a matcher should hopefully not change any Annex
state.

This does allow for eg `git-annex info somefile --include=*.ext`
although why someone would want to do that I don't really know. But it
seems to make sense to allow it.
But, consider: `git-annex info ./somefile --include=somefile`
This does not match, so will not display info about somefile.
If the user really wants to, they can `--include=./somefile`.

Using matching options like --copies or --in=remote seems likely to be
slower than git-annex find with those options, because unlike such
commands, info does not have optimised streaming through the matcher.

Note that `git-annex info remote` is not the same as
`git-annex info --in remote`. The former shows info about all files in
the remote. The latter shows local keys that are also in that remote.
The output should make that clear, but this still seems like a point
where users could get confused.

Sponsored-by: Jochen Bartl on Patreon

Command/Unused.hs

@@ -183,12 +183,10 @@ excludeReferenced refspec ks = runbloomfilter withKeysReferencedM ks
 	runfilter a l = a l
 	runbloomfilter a = runfilter $ \l -> bloomFilter l <$> genBloomFilter a
 
-{- Given an initial value, folds it with each key referenced by
- - files in the working tree. -}
-withKeysReferenced :: v -> (Key -> v -> v) -> Annex v
-withKeysReferenced initial a = withKeysReferenced' Nothing initial folda
-  where
-	folda k _ v = return $ a k v
+{- Given an initial value, accumulates the value over each key
+ - referenced by files in the working tree. -}
+withKeysReferenced :: v -> (Key -> RawFilePath -> v -> Annex v) -> Annex v
+withKeysReferenced initial = withKeysReferenced' Nothing initial
 
 {- Runs an action on each referenced key in the working tree. -}
 withKeysReferencedM :: (Key -> Annex ()) -> Annex ()