Primitives · raise: what opens inside a dialog lies over it

gpui 0.2.2 asserts on a deferred draw inside another, and every dialog,
sheet and popover draws inside one, so opening a date field in the
snooze or schedule dialog panicked, as would any list, menu or picker
opened in an overlay. primitives::raise replaces each deferred draw:
at the top it defers as before; inside something raised it leaves a
placeholder in the tree, and its layer lays it out on its own, then
draws it last. check.sh refuses gpui's deferred anywhere else.

The time dialog's rule is now times::ahead, tested for a moment
behind, now itself, a moment ahead and another zone; a gpui test picks
yesterday in the snooze dialog, sees that it has passed and that
nothing is sent, then picks two days ahead and hears that moment.

scripts/check.sh

@@ -15,4 +15,6 @@ done
 components=$(find src -name '*.rs' ! -path 'src/theme/*' ! -path 'src/motion/*' ! -path '*/tests/*' ! -name 'tests.rs')
 raw=$(awk '/#\[cfg\(test\)\]/{nextfile} /(^|[^.[:alnum:]_])px\(/{print FILENAME":"FNR": "$0}' $components)
 [ -z "$raw" ] || { echo "raw px in components:"; echo "$raw"; fail=1; }
+deferred=$(grep -rn 'deferred(' src --include='*.rs' | grep -v '^src/primitives/layer.rs' || true)
+[ -z "$deferred" ] || { echo "gpui deferred outside primitives::raise:"; echo "$deferred"; fail=1; }
 exit $fail