Update lfetool v2 to use new module metadata functions moved into lfe-utils

[oubiwann]

See ticket https://github.com/lfe/lfe-utils/issues/10.

[oubiwann]

In particular, src/lfetool-util.lfe needs to be updated once several of its functions have been moved into lutil (see issue #97).

And in src/lfetool-plugin.lfe, perhaps the following can be updated to use lutil functions:

• get-plugin-beam/1
• get-plugin-attributes/1
• get-plugin-behaviour/2
• get-plugin-beams/1
• filtered-plugins/1
• filtered-cmd-helps/1
• get-loaded-plugin-beams/0
• get-loaded-cmd-help-beams/0
• get-loaded-plugin-modules/0
• get-loaded-cmd-help-modules/0
• get-loaded-plugin-names/0