Action to replace (all-defined-out) provide with explicit list of items

[bluebear94]

This would replace an (all-defined-out) clause with all of the identifiers that would be exported.

[dannypsnl]

To get information, this is quite easy:

1. using get-definitions in doc-trace.rkt
2. get keys as defined identifiers of the current module
3. replace all-defined-out with the list

Some problems I can think out immediately are

1. What if all-defined-out and some exported duplicated? e.g. provide foo (all-defined-out)
2. export which phase? The layer is important in racket