Raw sends (api.jmap.sendRaw and submitRaw) now always lose label headers
a plugin wrote while the organisation uses labels. A crypto takeover is
matched to its raw send by a labelToken the composer puts in the
onComposeSend request (plugins that don't pass it back are matched by
identity, and refused when two takeovers are open), not by comparing
subjects. A raw send outside a takeover gets the default label, or is
refused when a label is required. The extra header is folded on the raw
path. The takeover code moves to lib/outgoing/classification-raw.ts;
the old test that let a raw send outside a takeover through unlabelled
now expects the forged header to be removed.
A sent message brought back by Undo, Cancel and edit or edit-as-new
reopened with the default label, because only drafts carried the
X-Bulwark-Label marker; it now falls back to the SIO-Label it went out
with. A reply, quick reply or plugin forward takes over the original's
label only when an internal sender set it and never one below the
default, since anyone outside can write the header. The tests written
for the earlier rule (any received label counts) now pass an internal
sender, which is why their originals changed.