External Tools: Translate name and category

The external tools internally are stored in an ini-like file format:

[Tool 0]
category=Git
name=git-cola
...

This patch adds grep/sed magic following how we extract translatable strings from json files in KTextEditor (indenter, scripts).

Running the two grep lines create output like:

// i18n: file: 8
i18nc("External tool category", "Git");

This output is then extracted with the XGETTEXT call a line later.