Some merge conflicts can't be resolved by editing markers in the merge view;
they require a dialog that picks one side (the "non-textual" conflicts like
DD/AU/UA/UD/DU). Both `enter` and, soon, `space` need to recognize these, so
pull the test into a shared predicate and rename handleNonInlineConflict to
openConflictResolutionMenu to match.
Restructure EnterFile so the predicate is checked first, ahead of the submodule
and inline-conflict branches. This is its final shape: upcoming commits only add
the submodule case to the predicate, with no further reordering. Behavior is
unchanged here, since the predicate is currently false for submodules.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>