i18n: translate the whole-thread actions, shipped as English in 0.24.0

Item 108 added five whole-thread actions and their submenu last session and
never refreshed the translation, so fifteen strings had no Italian: every
entry under "Whole thread", every undo text those actions push, and their
tooltips. lrelease silently DROPS an unfinished string and ships the source
text instead, so an Italian UI showed an English submenu and English undo
entries with nothing reporting a problem.

Found by running lupdate after adding this session's own strings: it reported
19 new, of which only three were mine. The gap is the reason ctest -R
translations exists, and it did not catch this because the .ts file was never
regenerated after item 108 landed.

Also translates the Config warning about an unparseable `language` value,
which had been untranslated since the i18n audit.

lrelease now reports 373 finished, 0 unfinished. The submenu was read in a
running LANG=it_IT build and confirmed correct.

0 files changed, 0 insertions, 0 deletions