Updater (cmd-line): add the 'list-local-only' command

This command allows you to list the files that have been installed locally
(i.e. not coming from any configured update site). This comes in handy in case
you need to investigate someone else's local installation, e.g. to check for
extra plugins that could be included in a personal update site.
Updater (cmd-line): add closing parenthesis
Merge branch 'updater-typos' of https://github.com/imcf/imagej

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Merge branch 'updater-list-local-only' of https://github.com/imcf/imagej

This adds the 'list-local-only' subcommand to the command-line updater.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>