tmpfiles: make t and a globby, add their recursive versions T and A

For types which adapt existing files it is generally more useful to accept
globs.

In analogy to z and Z, add recursive versions using uppercase letters.

Technically, making a accept globs is backwards incompatible, but in
practice it probably isn't yet widely used and we can assume that most
people don't create files with wildcards in names.

Functions which are used as callbacks, but not directly on items, are
renamed not to have "item_" prefix.